Add MOUSEKEY_WHEEL_DELTA documentation (#21493)

docs/feature_mouse_keys.md

@@ -67,6 +67,7 @@ This is the default mode. You can adjust the cursor and scrolling acceleration u
 |`MOUSEKEY_TIME_TO_MAX`      |30     |Time until maximum cursor speed is reached               |
 |`MOUSEKEY_WHEEL_DELAY`      |10     |Delay between pressing a wheel key and wheel movement    |
 |`MOUSEKEY_WHEEL_INTERVAL`   |80     |Time between wheel movements                             |
+|`MOUSEKEY_WHEEL_DELTA`      |1      |Wheel movement step size                                 |
 |`MOUSEKEY_WHEEL_MAX_SPEED`  |8      |Maximum number of scroll steps per scroll action         |
 |`MOUSEKEY_WHEEL_TIME_TO_MAX`|40     |Time until maximum scroll speed is reached               |
 

quantum/mousekey.h

@@ -44,9 +44,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #            define MOUSEKEY_MOVE_DELTA 8
 #        endif
 #    endif
-#    ifndef MOUSEKEY_WHEEL_DELTA
-#        define MOUSEKEY_WHEEL_DELTA 1
-#    endif
 #    ifndef MOUSEKEY_DELAY
 #        if defined(MK_KINETIC_SPEED)
 #            define MOUSEKEY_DELAY 5
@@ -85,6 +82,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #    ifndef MOUSEKEY_WHEEL_INTERVAL
 #        define MOUSEKEY_WHEEL_INTERVAL 80
 #    endif
+#    ifndef MOUSEKEY_WHEEL_DELTA
+#        define MOUSEKEY_WHEEL_DELTA 1
+#    endif
 #    ifndef MOUSEKEY_WHEEL_MAX_SPEED
 #        define MOUSEKEY_WHEEL_MAX_SPEED 8
 #    endif