[Proposal?] Allow RGB Underglow to turn off when host is idle/asleep (#2104)

* Add RGB Underglow Sleeping

* Add RGBLIGHT_SLEEP to toggle/control RGB light behavior

* Update rgb docs

* Update for RGB disable command

keyboards/orthodox/keymaps/drashna/config.h

@@ -64,6 +64,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define RGBLIGHT_EFFECT_KNIGHT_LENGTH 2
 #define RGBLIGHT_EFFECT_SNAKE_LENGTH 2
 #define RGBLIGHT_EFFECT_BREATHE_CENTER 1
+#define RGBLIGHT_SLEEP
 #endif // RGBLIGHT_ENABLE
 
 #ifdef AUDIO_ENABLE