Add a convention about file names to project conventions (#2886)
Add a convention about file names to project conventions (#2886)

* added a convention about file names to project conventions

* Qualified the convention for files to applicable to Go files only

* replaced should with must in the file name convention

* must use underscores for Go file names

frankbu/istio,frankbu/istio,geeknoid/istio,frankbu/istio,smawson/istio,geeknoid/istio,istio/istio,smawson/istio,geeknoid/istio,frankbu/istio,istio/istio,smawson/istio,smawson/istio,istio/istio,frankbu/istio,istio/istio,smawson/istio,geeknoid/istio,istio/istio,frankbu/istio,geeknoid/istio,geeknoid/istio,smawson/istio