Type searching added to applications menu.

docs/user.md

@@ -15,6 +15,12 @@ activates it and closes the menu. Escape or the Cancel button closes the menu
 without changing the selection. Tab and Shift+Tab move between the list, Cancel,
 and the tab selector. The active override is initially selected.
 
+Type the start of a name to jump to it: **n** selects NetworkManager, then **i**
+selects Ninjam. Searching ignores letter case and does not activate the item.
+Backspace removes a search character; Control+Backspace clears the search.
+Up, Down, or moving focus away from the list also clears the search. Unmatched
+characters announce **No matches** and leave the last matching search intact.
+
 Start the application normally, then select its override. This menu does not
 launch programs. Choose **Default** to restore the settings and reading regions
 that were in effect before the override. Overrides are built into Fenrir and