spec: clarify sentence about non-constant shifts
spec: clarify sentence about non-constant shifts

Fixes #10514.

Change-Id: Iae95a304d3ebb1ed82567aa234e05dc434db984f
Reviewed-on: https://go-review.googlesource.com/13098
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>
Reviewed-by: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

mdp/go,Badredapple/go,kevinc0825/go,jdeng/go,myPublicGit/go,Young55555/go,GeorgiCodes/go,snowsnail/go,willjunspecial/go,kim-racktop/go,samanalysis/go,NunoEdgarGub1/go,likesea/go,samanalysis/go,fjballest/golang,likesea/go,undergrowthlinear/go,jdhenke/go,zhangg/go,constantine001/go,theass/go,linux-on-ibm-z/go,odeke-em/go,goodlang/good,Endika/go,arschles/go-1,cloudflare/go,goodlang/good,codestation/go,andrewchambers/go,alash3al/go,honsiorovskyi/go,miolini/go,ichu501/go,devpadawan/go,jacobhaven/go,jdhenke/go,GeorgiCodes/go,zhangg/go,theass/go,codestation/go,XuYunnan/go,skatsuta/go,yuhengye/go,Endika/go,suncycheng/go,Endika/go,odeke-em/go,zhangg/go,jacobxk/go,g522342435/go,Samurais/go,alash3al/go,wangfakang/go-1,WIZARD-CXY/go,deft-code/go,cookerzhu/go,kevinc0825/go,gdey/go,XuYunnan/go,gdey/go,CodyGuo/go,nakedgc/go,cyberroadie/go,nawawi/go,theif519/go,golang/go,mwhudson/go,CAFxX/go,vishsingh/go,zhangg/go,shines77/go,jdeng/go,fjballest/golang,rentongzhang/go,jonathanmarvens/go,Samurais/go,CiscoCloud/go,polyverse-security/go,xiuzhifu/go,mdp/go,NichoZhang/go,jacobxk/go,yangzhongj/go,famorted/go,lihuanghai/go,miolini/go,kim-racktop/go,CarterTsai/go,NunoEdgarGub1/go,JioCloud/go,donnel6809/go,sinuos/go,xujianhai/go,WIZARD-CXY/go,xiaobodu/go,joshsammut/go,alex-zhang/go,sosop/go,albertjin/golang-go,nawawi/go,sndnvaps/go,ObjectiveJoe/go,joshsammut/go,jdeng/go,slavau/go,suncycheng/go,malvira/go,cainiaocome/go,undergrowthlinear/go,beealone/go,mbrukman/go,greyhwndz/go,nakedgc/go,miolini/go,mgyenik/go,mikekap/go,NichoZhang/go,albertjin/golang-go,derekmarcotte/go,devpadawan/go,jonahglover/go,arschles/go-1,arschles/golang-go,deft-code/go,fjballest/golang,cyberroadie/go,jefby/go,zouchao2010/go,Stan-Lin-/go,jacobsa/go,myPublicGit/go,momchil-velikov/go,samanalysis/go,Badredapple/go,CiscoCloud/go,chinanjjohn2012/go,jacobxk/go,4ad/go,jonathanmarvens/go,andrewchambers/go,GeorgiCodes/go,yasarkunduz/go,arschles/golang-go,sosop/go,ericsnowcurrently/go,donnel6809/go,alash3al/go,ericsnowcurrently/go,binarycrusader/go,albertjin/golang-go,arschles/go-1,odeke-em/go,GeorgiCodes/go,yangzhongj/go,slavau/go,rachtsingh/gogojuice,dafyddcrosby/go,sndnvaps/go,roth1002/go,danielsoro/go,mikekap/go,Jordanzuo/go,monetate/go,famorted/go,jameskumar/go,WIZARD-CXY/go,uileyar/go,monetate/go,lihuanghai/go,jonahglover/go,CodyGuo/go,mbrukman/go,famorted/go,stormltf/go,snowsnail/go,akutz/go,sosop/go,binarycrusader/go,rachtsingh/gogojuice,springning/go,Pulgafree/go,vsekhar/elastic-go,mgyenik/go,famorted/go,jacobhaven/go,monetate/go,vanloswang/go,ericsnowcurrently/go,cloudflare/go,andrewchambers/go,ErikDubbelboer/go,qskycolor/go,g522342435/go,devpadawan/go,nawawi/go,yuhengye/go,Jordanzuo/go,dafyddcrosby/go,4ad/go,dterei/go,constantine001/go,donnel6809/go,danycoro/go,chinanjjohn2012/go,stormltf/go,skatsuta/go,CAFxX/go,skatsuta/go,derekmarcotte/go,jacobhaven/go,ifagnosticism/go,momchil-velikov/go,ObjectiveJoe/go,mikekap/go,yangzhongj/go,jonasi/go,danielsoro/go,Cofyc/go,zcwfeng/go,ichu501/go,greyhwndz/go,roth1002/go,4ad/go,xiuzhifu/go,mgyenik/go,zouchao2010/go,cainiaocome/go,derekmarcotte/go,cookerzhu/go,jmptrader/go,dpatel06/go,vsekhar/elastic-go,ImJasonH/go,vanloswang/go,ErikDubbelboer/go,gdey/go,josharian/go,mgyenik/go,famorted/go,codestation/go,arschles/golang-go,zcwfeng/go,mbrukman/go,myPublicGit/go,andrewchambers/go,dterei/go,GeorgiCodes/go,skatsuta/go,sndnvaps/go,4ad/go,likesea/go,Pulgafree/go,polyverse-security/go,famorted/go,constantine001/go,lihuanghai/go,derekmarcotte/go,goodlang/good,andrewchambers/go,AALEKH/go,vanloswang/go,deft-code/go,gdey/go,slavau/go,famorted/go,snowsnail/go,arschles/go-1,vanloswang/go,shines77/go,myPublicGit/go,roth1002/go,malvira/go,honsiorovskyi/go,mikekap/go,g522342435/go,roth1002/go,WIZARD-CXY/go,goodlang/good,jonahglover/go,alex-zhang/go,Young55555/go,honsiorovskyi/go,polyverse-security/go,uileyar/go,josharian/go,leeric92/go,XuYunnan/go,dafyddcrosby/go,danielsoro/go,alex-zhang/go,theif519/go,binarycrusader/go,monetate/go,JioCloud/go,jdhenke/go,uileyar/go,b54898533/go,CarterTsai/go,b54898533/go,alash3al/go,josharian/go,ErikDubbelboer/go,golang/go,snowsnail/go,constantine001/go,binarycrusader/go,jasonxiong/go,joshsammut/go,likesea/go,honsiorovskyi/go,cainiaocome/go,Samurais/go,xiuzhifu/go,josharian/go,willjunspecial/go,Badredapple/go,theass/go,Young55555/go,zouchao2010/go,nawawi/go,jasonxiong/go,danielsoro/go,skatsuta/go,ImJasonH/go,CiscoCloud/go,zouchao2010/go,lihuanghai/go,nakedgc/go,cookerzhu/go,samanalysis/go,derekmarcotte/go,JioCloud/go,akutz/go,mgyenik/go,yuhengye/go,kevinc0825/go,ErikDubbelboer/go,joshsammut/go,Pulgafree/go,joshsammut/go,b54898533/go,kevinc0825/go,zhangg/go,stormltf/go,springning/go,arschles/golang-go,undergrowthlinear/go,rentongzhang/go,binarycrusader/go,jefby/go,linux-on-ibm-z/go,jmptrader/go,ganboing/go-esx,slavau/go,rachtsingh/gogojuice,ObjectiveJoe/go,jonasi/go,albertjin/golang-go,slavau/go,rachtsingh/gogojuice,uileyar/go,albertjin/golang-go,deft-code/go,nakedgc/go,slavau/go,ichu501/go,Charlesdong/go-1,mwhudson/go,CAFxX/go,yasarkunduz/go,vsdutka/go,vishsingh/go,NichoZhang/go,qskycolor/go,danycoro/go,Cofyc/go,jacobhaven/go,mwhudson/go,fjballest/golang,mgyenik/go,polyverse-security/go,kim-racktop/go,zouchao2010/go,wangfakang/go-1,fjballest/golang,binarycrusader/go,NunoEdgarGub1/go,zhangg/go,cookerzhu/go,b54898533/go,Badredapple/go,Young55555/go,lihuanghai/go,leeric92/go,jonahglover/go,donnel6809/go,vsdutka/go,mdp/go,yangzhongj/go,derekmarcotte/go,derekmarcotte/go,odeke-em/go,josharian/go,albertjin/golang-go,xiaobodu/go,xiuzhifu/go,wangfakang/go-1,ganboing/go-esx,CiscoCloud/go,leeric92/go,NunoEdgarGub1/go,Endika/go,zcwfeng/go,cloudflare/go,linux-on-ibm-z/go,jacobsa/go,jdhenke/go,springning/go,Badredapple/go,willjunspecial/go,polyverse-security/go,GeorgiCodes/go,NichoZhang/go,jdeng/go,zouchao2010/go,cyberroadie/go,springning/go,alash3al/go,myPublicGit/go,alash3al/go,springning/go,JioCloud/go,ErikDubbelboer/go,b54898533/go,CiscoCloud/go,kakuhiroshi/go,alash3al/go,WIZARD-CXY/go,malvira/go,AALEKH/go,yuhengye/go,cyberroadie/go,sndnvaps/go,mdp/go,jdhenke/go,linux-on-ibm-z/go,vanloswang/go,fjballest/golang,jacobsa/go,jacobxk/go,XuYunnan/go,xujianhai/go,undergrowthlinear/go,arschles/go-1,dterei/go,cainiaocome/go,dpatel06/go,ganboing/go-esx,polyverse-security/go,kevinc0825/go,golang/go,jonahglover/go,mbrukman/go,XuYunnan/go,golang/go,jacobsa/go,CodyGuo/go,cainiaocome/go,constantine001/go,cloudflare/go,cloudflare/go,akutz/go,jefby/go,CAFxX/go,ichu501/go,jacobsa/go,ericsnowcurrently/go,suncycheng/go,AALEKH/go,sinuos/go,vanloswang/go,vsdutka/go,ErikDubbelboer/go,sosop/go,snowsnail/go,donnel6809/go,Badredapple/go,goodlang/good,leeric92/go,zouchao2010/go,mdp/go,akutz/go,jonathanmarvens/go,AALEKH/go,vsdutka/go,binarycrusader/go,NichoZhang/go,skatsuta/go,andrewchambers/go,Charlesdong/go-1,ichu501/go,alex-zhang/go,CiscoCloud/go,ichu501/go,NunoEdgarGub1/go,malvira/go,vanloswang/go,Stan-Lin-/go,theif519/go,momchil-velikov/go,dafyddcrosby/go,theif519/go,uileyar/go,linux-on-ibm-z/go,mwhudson/go,dpatel06/go,jameskumar/go,CAFxX/go,dpatel06/go,goodlang/good,wangfakang/go-1,vsekhar/elastic-go,uileyar/go,Young55555/go,golang/go,myPublicGit/go,ganboing/go-esx,alex-zhang/go,vsekhar/elastic-go,4ad/go,shines77/go,sinuos/go,jonasi/go,vsekhar/elastic-go,nawawi/go,JioCloud/go,christopher-henderson/Go,malvira/go,Endika/go,alash3al/go,roth1002/go,skatsuta/go,roth1002/go,dafyddcrosby/go,mwhudson/go,theass/go,greyhwndz/go,cyberroadie/go,famorted/go,polyverse-security/go,greyhwndz/go,yasarkunduz/go,ImJasonH/go,likesea/go,lihuanghai/go,golang/go,greyhwndz/go,xujianhai/go,g522342435/go,gdey/go,nakedgc/go,miolini/go,jonathanmarvens/go,dafyddcrosby/go,g522342435/go,deft-code/go,nawawi/go,sosop/go,jacobxk/go,chinanjjohn2012/go,gdey/go,jefby/go,GeorgiCodes/go,dafyddcrosby/go,vsekhar/elastic-go,likesea/go,goodlang/good,danielsoro/go,jonasi/go,alex-zhang/go,jacobxk/go,cloudflare/go,rentongzhang/go,ImJasonH/go,Endika/go,mbrukman/go,g522342435/go,mikekap/go,JioCloud/go,malvira/go,joshsammut/go,jonathanmarvens/go,kakuhiroshi/go,skatsuta/go,sosop/go,cainiaocome/go,CarterTsai/go,qskycolor/go,samanalysis/go,devpadawan/go,donnel6809/go,AALEKH/go,Jordanzuo/go,ifagnosticism/go,Jordanzuo/go,jefby/go,ifagnosticism/go,Pulgafree/go,ObjectiveJoe/go,jdeng/go,yangzhongj/go,odeke-em/go,Samurais/go,zcwfeng/go,ImJasonH/go,mwhudson/go,yuhengye/go,Stan-Lin-/go,yasarkunduz/go,danycoro/go,ifagnosticism/go,jameskumar/go,Jordanzuo/go,NunoEdgarGub1/go,shines77/go,Young55555/go,sinuos/go,joshsammut/go,stormltf/go,arschles/golang-go,sndnvaps/go,wangfakang/go-1,rentongzhang/go,sndnvaps/go,gdey/go,mgyenik/go,rachtsingh/gogojuice,miolini/go,xujianhai/go,Jordanzuo/go,vishsingh/go,jonathanmarvens/go,4ad/go,chinanjjohn2012/go,mdp/go,sinuos/go,xiaobodu/go,vsdutka/go,cainiaocome/go,springning/go,jmptrader/go,mbrukman/go,dterei/go,linux-on-ibm-z/go,fjballest/golang,Cofyc/go,ganboing/go-esx,constantine001/go,jacobhaven/go,sndnvaps/go,honsiorovskyi/go,beealone/go,jacobsa/go,kakuhiroshi/go,monetate/go,CarterTsai/go,codestation/go,yangzhongj/go,myPublicGit/go,dpatel06/go,ifagnosticism/go,b54898533/go,golang/go,mdp/go,WIZARD-CXY/go,jonahglover/go,xiuzhifu/go,likesea/go,monetate/go,kim-racktop/go,slavau/go,suncycheng/go,deft-code/go,beealone/go,vishsingh/go,jefby/go,CarterTsai/go,vsekhar/elastic-go,theass/go,kim-racktop/go,vishsingh/go,mikekap/go,miolini/go,suncycheng/go,CAFxX/go,kakuhiroshi/go,jacobhaven/go,chinanjjohn2012/go,ObjectiveJoe/go,arschles/golang-go,snowsnail/go,qskycolor/go,danycoro/go,willjunspecial/go,snowsnail/go,jdhenke/go,jacobhaven/go,qskycolor/go,stormltf/go,ganboing/go-esx,AALEKH/go,beealone/go,ifagnosticism/go,andrewchambers/go,jonasi/go,zcwfeng/go,shines77/go,monetate/go,shines77/go,sosop/go,CiscoCloud/go,CodyGuo/go,springning/go,theif519/go,rentongzhang/go,roth1002/go,arschles/go-1,nakedgc/go,undergrowthlinear/go,slavau/go,rentongzhang/go,ObjectiveJoe/go,beealone/go,greyhwndz/go,vishsingh/go,jameskumar/go,ImJasonH/go,nawawi/go,dterei/go,vsekhar/elastic-go,willjunspecial/go,devpadawan/go,jameskumar/go,jameskumar/go,cyberroadie/go,b54898533/go,jasonxiong/go,Pulgafree/go,jonahglover/go,dterei/go,Jordanzuo/go,cyberroadie/go,jmptrader/go,xujianhai/go,zhangg/go,cookerzhu/go,greyhwndz/go,kakuhiroshi/go,jmptrader/go,xiuzhifu/go,suncycheng/go,jonathanmarvens/go,malvira/go,springning/go,ichu501/go,Cofyc/go,codestation/go,willjunspecial/go,deft-code/go,jasonxiong/go,NunoEdgarGub1/go,mbrukman/go,yuhengye/go,theass/go,cookerzhu/go,jasonxiong/go,theif519/go,sinuos/go,arschles/golang-go,samanalysis/go,CodyGuo/go,yasarkunduz/go,WIZARD-CXY/go,b54898533/go,CarterTsai/go,CodyGuo/go,alex-zhang/go,Pulgafree/go,shines77/go,danycoro/go,kim-racktop/go,deft-code/go,Pulgafree/go,ichu501/go,beealone/go,xiaobodu/go,CiscoCloud/go,dpatel06/go,cloudflare/go,dpatel06/go,GeorgiCodes/go,donnel6809/go,ErikDubbelboer/go,jmptrader/go,uileyar/go,jasonxiong/go,golang/go,undergrowthlinear/go,undergrowthlinear/go,jonahglover/go,odeke-em/go,sinuos/go,linux-on-ibm-z/go,xujianhai/go,lihuanghai/go,zcwfeng/go,roth1002/go,nawawi/go,Samurais/go,arschles/go-1,Stan-Lin-/go,cyberroadie/go,wangfakang/go-1,qskycolor/go,devpadawan/go,Stan-Lin-/go,xiuzhifu/go,miolini/go,Samurais/go,Charlesdong/go-1,suncycheng/go,Endika/go,cookerzhu/go,sinuos/go,samanalysis/go,Stan-Lin-/go,zcwfeng/go,jefby/go,NichoZhang/go,binarycrusader/go,dpatel06/go,donnel6809/go,jdeng/go,jasonxiong/go,jacobxk/go,Stan-Lin-/go,mikekap/go,stormltf/go,g522342435/go,ericsnowcurrently/go,4ad/go,kim-racktop/go,Samurais/go,danycoro/go,g522342435/go,honsiorovskyi/go,rachtsingh/gogojuice,NichoZhang/go,Charlesdong/go-1,chinanjjohn2012/go,Young55555/go,Charlesdong/go-1,rachtsingh/gogojuice,sndnvaps/go,chinanjjohn2012/go,vsdutka/go,Badredapple/go,jonasi/go,ImJasonH/go,malvira/go,vanloswang/go,Cofyc/go,fjballest/golang,ObjectiveJoe/go,suncycheng/go,momchil-velikov/go,zhangg/go,monetate/go,CodyGuo/go,rentongzhang/go,xiaobodu/go,josharian/go,undergrowthlinear/go,Samurais/go,andrewchambers/go,mbrukman/go,albertjin/golang-go,lihuanghai/go,derekmarcotte/go,XuYunnan/go,jmptrader/go,kevinc0825/go,Stan-Lin-/go,ericsnowcurrently/go,jdhenke/go,codestation/go,zouchao2010/go,constantine001/go,odeke-em/go,WIZARD-CXY/go,odeke-em/go,kevinc0825/go,Jordanzuo/go,jonasi/go,honsiorovskyi/go,akutz/go,vsdutka/go,kakuhiroshi/go,stormltf/go,cloudflare/go,xiaobodu/go,rentongzhang/go,kim-racktop/go,wangfakang/go-1,mwhudson/go,jacobsa/go,beealone/go,codestation/go,danycoro/go,danielsoro/go,ganboing/go-esx,wangfakang/go-1,gdey/go,samanalysis/go,ImJasonH/go,AALEKH/go,xujianhai/go,theif519/go,qskycolor/go,danielsoro/go,linux-on-ibm-z/go,yangzhongj/go,CAFxX/go,momchil-velikov/go,ericsnowcurrently/go,jmptrader/go,chinanjjohn2012/go,JioCloud/go,Cofyc/go,miolini/go,kakuhiroshi/go,4ad/go,mwhudson/go,devpadawan/go,josharian/go,jacobhaven/go,xujianhai/go,yuhengye/go,stormltf/go,codestation/go,yasarkunduz/go,Pulgafree/go,dafyddcrosby/go,ifagnosticism/go,CodyGuo/go,Charlesdong/go-1,CarterTsai/go,dterei/go,xiuzhifu/go,theif519/go,honsiorovskyi/go,XuYunnan/go,akutz/go,goodlang/good,NunoEdgarGub1/go,momchil-velikov/go,mdp/go,momchil-velikov/go,theass/go,yuhengye/go,Endika/go,AALEKH/go,cainiaocome/go,jdeng/go,leeric92/go,xiaobodu/go,kevinc0825/go,jacobxk/go,leeric92/go,cookerzhu/go,akutz/go,devpadawan/go,leeric92/go,jameskumar/go,arschles/go-1,likesea/go,CarterTsai/go,yasarkunduz/go,jdeng/go,Charlesdong/go-1,polyverse-security/go,alex-zhang/go,nakedgc/go,ifagnosticism/go,jasonxiong/go,akutz/go,greyhwndz/go,Young55555/go,myPublicGit/go,zcwfeng/go,danielsoro/go,jefby/go,qskycolor/go,ericsnowcurrently/go,momchil-velikov/go,josharian/go,xiaobodu/go,Charlesdong/go-1,jacobsa/go,jonasi/go,Badredapple/go,arschles/golang-go,theass/go,yangzhongj/go,vishsingh/go,jameskumar/go,constantine001/go,willjunspecial/go,albertjin/golang-go,willjunspecial/go,beealone/go,joshsammut/go,ErikDubbelboer/go,CAFxX/go,uileyar/go,ObjectiveJoe/go,Cofyc/go,yasarkunduz/go,mgyenik/go,Cofyc/go,rachtsingh/gogojuice,kakuhiroshi/go,shines77/go,snowsnail/go,ganboing/go-esx,vsdutka/go,leeric92/go,dterei/go,mikekap/go,danycoro/go,jonathanmarvens/go,JioCloud/go,nakedgc/go,XuYunnan/go,sosop/go,NichoZhang/go,vishsingh/go,jdhenke/go