'?' entry for 'O' help

Update the menu for the help command to change
  "i - using the 'O' command to set options"
to
  "i - using the '#optionsfull' or 'm O' command to set options"
(examples assume default key bindings but the actual help menu shows
currently bound keys; the "or 'foo'" part is omitted if #optionsfull
is bound to a key).

dat/opthelp should probably be updated to describe how doset_simple
works since that is different from normal menus and explicitly
contradicts the existing description for boolean settings being
deferred until the menu gets dismissed.  Any changes need to make
sense if displayed in the context of picking '?' in #optionsfull.
Maybe a separate help file and separate entry for it in '?' menu?

src/cmd.c

@@ -2612,7 +2612,8 @@ struct ext_func_tab extcmdlist[] = {
     { 'S',    "save", "save the game and exit",
               dosave, IFBURIED | GENERALCMD | NOFUZZERCMD, NULL },
     { '\0',   "saveoptions", "save the game configuration",
-              do_write_config_file, IFBURIED | GENERALCMD | NOFUZZERCMD, NULL },
+              do_write_config_file,
+              IFBURIED | GENERALCMD | NOFUZZERCMD, NULL },
     { 's',    "search", "search for traps and secret doors",
               dosearch, IFBURIED | CMD_M_PREFIX, "searching" },
     { '*',    "seeall", "show all equipment in use",