docs: improvements to source code documentation (#1236)

src/video.h

@@ -1,7 +1,4 @@
-// Created by loki on 6/9/19.
-
-#ifndef SUNSHINE_VIDEO_H
-#define SUNSHINE_VIDEO_H
+#pragma once
 
 #include "input.h"
 #include "platform/common.h"
@@ -103,5 +100,3 @@ namespace video {
   int
   probe_encoders();
 }  // namespace video
-
-#endif  // SUNSHINE_VIDEO_H