os/signal: don't expect to be notified for os.Kill
os/signal: don't expect to be notified for os.Kill

os.Kill cannot be caught on Unix systems.
The example gives the false impression that it can.

Fixes #13080.

Change-Id: I3b9e6f38a38f437a463c5b869ae84a0d3fd23f72
Reviewed-on: https://go-review.googlesource.com/16467
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

mwhudson/go,malvira/go,ganboing/go-esx,gdey/go,Endika/go,suncycheng/go,cloudflare/go,odeke-em/go,fjballest/golang,kim-racktop/go,miolini/go,theif519/go,theif519/go,Endika/go,linux-on-ibm-z/go,4ad/go,fjballest/golang,ImJasonH/go,cloudflare/go,vanloswang/go,4ad/go,miolini/go,derekmarcotte/go,rachtsingh/gogojuice,fjballest/golang,Jordanzuo/go,sndnvaps/go,akutz/go,theif519/go,Samurais/go,nawawi/go,Cofyc/go,cyberroadie/go,binarycrusader/go,deft-code/go,CAFxX/go,malvira/go,cyberroadie/go,golang/go,miolini/go,codestation/go,codestation/go,Jordanzuo/go,suncycheng/go,odeke-em/go,binarycrusader/go,roth1002/go,Endika/go,fjballest/golang,cloudflare/go,kim-racktop/go,CAFxX/go,linux-on-ibm-z/go,mwhudson/go,fjballest/golang,momchil-velikov/go,ganboing/go-esx,kim-racktop/go,vanloswang/go,odeke-em/go,ganboing/go-esx,goodlang/good,theif519/go,kim-racktop/go,polyverse-security/go,odeke-em/go,Jordanzuo/go,ImJasonH/go,deft-code/go,cloudflare/go,kim-racktop/go,4ad/go,CAFxX/go,momchil-velikov/go,malvira/go,CAFxX/go,suncycheng/go,polyverse-security/go,sndnvaps/go,cloudflare/go,binarycrusader/go,odeke-em/go,sndnvaps/go,odeke-em/go,polyverse-security/go,josharian/go,sndnvaps/go,nawawi/go,4ad/go,malvira/go,CAFxX/go,Cofyc/go,momchil-velikov/go,polyverse-security/go,Jordanzuo/go,polyverse-security/go,cyberroadie/go,deft-code/go,nawawi/go,christopher-henderson/Go,golang/go,vsekhar/elastic-go,linux-on-ibm-z/go,deft-code/go,ImJasonH/go,gdey/go,codestation/go,Jordanzuo/go,Jordanzuo/go,vanloswang/go,fjballest/golang,Endika/go,josharian/go,Cofyc/go,momchil-velikov/go,vanloswang/go,deft-code/go,theif519/go,ganboing/go-esx,kim-racktop/go,Samurais/go,rachtsingh/gogojuice,golang/go,vanloswang/go,suncycheng/go,mwhudson/go,Samurais/go,derekmarcotte/go,Jordanzuo/go,fjballest/golang,CAFxX/go,golang/go,theif519/go,goodlang/good,Cofyc/go,nawawi/go,ImJasonH/go,vanloswang/go,suncycheng/go,Endika/go,josharian/go,suncycheng/go,miolini/go,odeke-em/go,gdey/go,miolini/go,polyverse-security/go,akutz/go,goodlang/good,binarycrusader/go,linux-on-ibm-z/go,roth1002/go,vsekhar/elastic-go,Cofyc/go,linux-on-ibm-z/go,linux-on-ibm-z/go,4ad/go,ganboing/go-esx,codestation/go,roth1002/go,deft-code/go,akutz/go,momchil-velikov/go,deft-code/go,goodlang/good,nawawi/go,rachtsingh/gogojuice,mwhudson/go,sndnvaps/go,gdey/go,malvira/go,Samurais/go,kim-racktop/go,gdey/go,josharian/go,ganboing/go-esx,mwhudson/go,suncycheng/go,cyberroadie/go,CAFxX/go,malvira/go,golang/go,Samurais/go,golang/go,4ad/go,rachtsingh/gogojuice,goodlang/good,derekmarcotte/go,vsekhar/elastic-go,kim-racktop/go,josharian/go,josharian/go,4ad/go,rachtsingh/gogojuice,Endika/go,ImJasonH/go,Endika/go,goodlang/good,Jordanzuo/go,ImJasonH/go,Cofyc/go,cloudflare/go,sndnvaps/go,ImJasonH/go,linux-on-ibm-z/go,miolini/go,nawawi/go,nawawi/go,derekmarcotte/go,codestation/go,golang/go,Endika/go,sndnvaps/go,vanloswang/go,derekmarcotte/go,akutz/go,derekmarcotte/go,binarycrusader/go,Samurais/go,akutz/go,miolini/go,Samurais/go,goodlang/good,codestation/go,codestation/go,derekmarcotte/go,akutz/go,momchil-velikov/go,Cofyc/go,malvira/go,cloudflare/go,binarycrusader/go,4ad/go,cloudflare/go,sndnvaps/go,codestation/go,vsekhar/elastic-go,theif519/go,roth1002/go,vanloswang/go,cyberroadie/go,mwhudson/go,Cofyc/go,fjballest/golang,rachtsingh/gogojuice,vsekhar/elastic-go,gdey/go,CAFxX/go,rachtsingh/gogojuice,josharian/go,gdey/go,ganboing/go-esx,cyberroadie/go,mwhudson/go,polyverse-security/go,momchil-velikov/go,roth1002/go,roth1002/go,nawawi/go,roth1002/go,cyberroadie/go,vsekhar/elastic-go,akutz/go,suncycheng/go,binarycrusader/go,roth1002/go,akutz/go,derekmarcotte/go,goodlang/good,ganboing/go-esx,gdey/go,mwhudson/go,odeke-em/go,deft-code/go,momchil-velikov/go,ImJasonH/go,josharian/go,theif519/go,vsekhar/elastic-go,vsekhar/elastic-go,rachtsingh/gogojuice,cyberroadie/go,golang/go,miolini/go,malvira/go,polyverse-security/go,binarycrusader/go,Samurais/go,linux-on-ibm-z/go