refactor: rename //:git-bug.go to //:main.go (#1373)

sudoforge created 

`main.go` is and always has been the conventional entrypoint for
binaries (this is actually true for libraries as well, e.g. some
internal
`//foo` package would typically have an entrypoint of `//foo:foo.go`)

Change-Id: Ic75db640b06dc5c39a8c88db0d9d73d78f39d772

Change summary

main.go | 0 
1 file changed

Detailed changes