doc: add note about cgo pointer passing rules to go1.6.txt
doc: add note about cgo pointer passing rules to go1.6.txt

Change-Id: I988d1b230ce516bf2997ec0932a854323b2bab7c
Reviewed-on: https://go-review.googlesource.com/17395
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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