group keybindings in built-in help text
group keybindings in built-in help text

Group them in roughly the same way as in the manual.  This makes
it a lot easier to locate a key binding more quickly.

tstack/lnav,tstack/lnav,sureshsundriyal/lnav,sureshsundriyal/lnav,tstack/lnav,sureshsundriyal/lnav,tstack/lnav,sureshsundriyal/lnav