input.conf: add context menu bindings

Rebind MENU to show the context menu. Shift+F10 is also bound because it
is a standard context menu binding.

MENU is not added to restore-old-bindings.conf because it is uncommon.

DOCS/man/mpv.rst

@@ -351,11 +351,14 @@ g-b
 g-r
     Show the values of all properties.
 
-g-m, MENU, Ctrl+p
+g-m, Ctrl+p
     Show a menu with miscellaneous entries.
 
 See `SELECT`_ for more information.
 
+MENU, Shift+F10
+    Show the context menu (see `CONTEXT MENU`_).
+
 (The following keys are valid if you have a keyboard with multimedia keys.)
 
 PAUSE

etc/input.conf

@@ -196,8 +196,9 @@
 #g-b script-binding select/select-binding
 #g-r script-binding select/show-properties
 #g-m script-binding select/menu
-#MENU script-binding select/menu
 #ctrl+p script-binding select/menu
+#MENU script-binding select/context-menu
+#Shift+F10 script-binding select/context-menu
 
 #Alt+KP1 add video-rotate -1 # rotate video counterclockwise by 1 degree
 #Alt+KP5 set video-rotate  0 # reset rotation