cmd/vet: add a README explaining the criteria for new checks
cmd/vet: add a README explaining the criteria for new checks

Correctness, Frequency, Precision.

Change-Id: I7f202c220aef8512d611dc04a4370b4a237f217c
Reviewed-on: https://go-review.googlesource.com/20003
Reviewed-by: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

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