Add help description to HELP
Add help description to RESPOND
Add help description to MEASURE_AXES_NOISE, TEST_RESONANCES and SHAPER_CALIBRATE
Add help description to PAUSE, RESUME, CLEAR_PAUSE and CANCEL_PRINT
Add help description to GET_POSITION
Add help description to SET_RETRACTION and GET_RETRACTION
Signed-off-by: Stefan Dej <meteyou@gmail.com>