DOCS/man/lua: document how to nest mp.input calls

Author: guidocella

DOCS/man/lua.rst

@@ -931,6 +931,12 @@ REPL.
     ``keep_open``
         Whether to keep the console open on submit. Defaults to ``false``.
 
+        .. warning::
+
+            This must be set to ``true`` to nest ``input.get()`` or
+            ``input.select()`` calls.
+
+
     ``opened``
         A callback invoked when the console is shown. This can be used to
         present a list of options with ``input.set_log()``.
@@ -1027,6 +1033,11 @@ REPL.
     ``keep_open``
         Whether to keep the console open on submit. Defaults to ``false``.
 
+        .. warning::
+
+            This must be set to ``true`` to nest ``input.get()`` or
+            ``input.select()`` calls.
+
     Example:
 
         ::