add caveats to README

README.md

@@ -9,4 +9,11 @@ framebuffer pixelflut server in C.
   to the framebuffer (ie put yourself in the `video` group)
 - go in something that wont fight you for the framebuffer,
   ie a tty
-- do `./fbflut`
+- do `./fbflut` (or `./fbflut <port>`)
+- connect with netcat or something, the default port is 1234
+
+## caveats
+- this writes directly to your framebuffer, which might not use (aa)rrggbb (bbggrraa is somewhat common).
+  if you have alpha trailing at the end, uncomment lines `42` and `43` to allow omitting it in `PX` lines
+- fbflut does not store its own buffer, the canvas is entirely stored in the framebuffer,
+  so be weary of other programs writing to it as thats the only copy