doc: revise help page with categories and more links
doc: revise help page with categories and more links

Fixes #12489

Change-Id: I25dd3f76e4cfe9a71b987c3b31445724568391e9
Reviewed-on: https://go-review.googlesource.com/18625
Reviewed-by: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

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