Update Keystrokes

Keystrokes.md

@@ -54,6 +54,7 @@ These keys are just like the band stack register buttons on the IC-7300 and will
 | F8 | Activate mode CW |
 | F9 | Activate mode USB-D |
 | F10 | Show build info in status bar |
+| F11 | Toggle full screen |
 | F12 | Tell radio to speak current frequency and mode |
 | F | Tell the radio to speak the current frequency |
 | M | Tell the radio to speak the current mode |