Manual DS4 mode: Allow Back/Select to trigger Touchpad click (#1772)

Co-authored-by: ReenigneArcher <42013603+ReenigneArcher@users.noreply.github.com>

docs/source/about/advanced_usage.rst

@@ -152,6 +152,23 @@ gamepad
    .. code-block:: text
 
       gamepad = auto
+      
+ds4_back_as_touchpad_click
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+**Description**
+   .. Hint:: Only applies when gamepad is set to ds4 manually. Unused in other gamepad modes. 
+
+   Allow Select/Back inputs to also trigger DS4 touchpad click. Useful for clients looking to emulate touchpad click
+   on Xinput devices.
+
+**Default**
+   ``enabled``
+
+**Example**
+   .. code-block:: text
+
+      ds4_back_as_touchpad_click = enabled
 
 back_button_timeout
 ^^^^^^^^^^^^^^^^^^^