Update Readme.md

Author: Motobug

Readme.md

@@ -22,6 +22,7 @@ This is a work-in-progress version of the Dolphin Emulator built for usage with
   * Client side music toggle in netplay window
 
 * To-Do
+  * Gamecube adapter polling rate in controller settings 
   * Spectator button in netplay window
   * Overwrite Dolphin updater functions with our own
   * "On SI Read" polling method