patch 8.2.0385: menu functionality insufficiently tested

Problem:    Menu functionality insufficiently tested.
Solution:   Add tests.  Add menu_info(). (Yegappan Lakshmanan, closes #5760)
diff --git a/runtime/doc/gui.txt b/runtime/doc/gui.txt
index 1a38496..41e20b1 100644
--- a/runtime/doc/gui.txt
+++ b/runtime/doc/gui.txt
@@ -578,9 +578,11 @@
 
 Special characters in a menu name:
 
+							*menu-shortcut*
 	&	The next character is the shortcut key.  Make sure each
 		shortcut key is only used once in a (sub)menu.  If you want to
 		insert a literal "&" in the menu name use "&&".
+							*menu-text*
 	<Tab>	Separates the menu name from right-aligned text.  This can be
 		used to show the equivalent typed command.  The text "<Tab>"
 		can be used here for convenience.  If you are using a real
@@ -954,7 +956,7 @@
 mappings, or put these lines in your gvimrc; "<C-R>" is CTRL-R, "<CR>" is
 the <CR> key.  |<>|)
 
-
+							*tooltips* *menu-tips*
 5.8 Tooltips & Menu tips
 
 See section |42.4| in the user manual.