[kitty] Add show_scrollback

.config/kitty/kitty.conf

@@ -1236,6 +1236,7 @@ map kitty_mod+page_down scroll_page_down
 map kitty_mod+home      scroll_home
 map kitty_mod+end       scroll_end
 map kitty_mod+f         launch --type=overlay --stdin-source=@screen_scrollback fzf --tac --no-sort --no-mouse -i
+map kitty_mod+h         show_scrollback
 
 #: You can pipe the contents of the current screen + history buffer as
 #: STDIN to an arbitrary program using the ``launch`` function. For