add module comments for vgo

cmd/frpc/main.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package main // "github.com/fatedier/frp/cmd/frpc"
 
 import (
 	"github.com/fatedier/frp/cmd/frpc/sub"

cmd/frps/main.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package main // "github.com/fatedier/frp/cmd/frps"
 
 import (
 	"github.com/fatedier/golib/crypto"