Update README add help text

README.md

@@ -90,3 +90,4 @@ The documentation was created using [doxygen](http://www.doxygen.org). It includ
  - Qt::Key makes no difference between normal numbers and the Numpad numbers. Most keyboards however require this. Thus, you can't register shortcuts for the numpad, unless you use a native shortcut.
  - Supports not all keys, but most of the common ones. There are differences between platforms and it depends on the Keyboard-Layout. "Delete", for example, works on windows and mac, but not on X11 (At least on my test machines). I tried to use OS-Functions where possible, but since the Qt::Key values need to be converted into native keys, there are some limitations. I can use need such a key, try using the native shortcut.
  - The registered keys will be "taken" by QHotkey. This means after a hotkey was cosumend by your application, it will not be sent to the active application. This is done this way by the operating systems and cannot be changed.
+- If you get a `QHotkey: Failed to register hotkey. Error: BadAccess (attempt to access private resource denied)` error on X11, this means you are trying to register a hotkey that is private to X11. Those keys simply cannot be registered using the normal API