fix(protoc-gen-go-errors): fix generated function comments have extra blank lines. (#2008)

cmd/protoc-gen-go-errors/template.go

@@ -8,7 +8,7 @@ import (
 var errorsTemplate = `
 {{ range .Errors }}
 
-{{if .HasComment}}{{.Comment}}{{end}}
+{{ if .HasComment }}{{ .Comment }}{{ end -}}
 func Is{{.CamelValue}}(err error) bool {
 	if err == nil {
 		return false
@@ -17,7 +17,7 @@ func Is{{.CamelValue}}(err error) bool {
 	return e.Reason == {{ .Name }}_{{ .Value }}.String() && e.Code == {{ .HTTPCode }} 
 }
 
-{{if .HasComment}}{{.Comment}}{{end}}
+{{ if .HasComment }}{{ .Comment }}{{ end -}}
 func Error{{ .CamelValue }}(format string, args ...interface{}) *errors.Error {
 	 return errors.New({{ .HTTPCode }}, {{ .Name }}_{{ .Value }}.String(), fmt.Sprintf(format, args...))
 }