Typo fixes

Typos were fixed in bin/md2html.cfg, bin/subst.default.sh,
nojs-menu.html and nojs-menu.md.

The nojs-menu.html now links to bin/index.html and inc/index.html but
the rest of the html files for now do not. It seems like it might be
good if they do, at least bin/index.html, but if that is decided against
this can be rolled back instead.

bin/subst.default.sh

@@ -142,7 +142,7 @@ export USAGE="usage: $0 [-h] [-v level] [-V] [-d topdir] [-D docroot/] [-n] [-N]
 	-e string	output string, followed by newline, to stderr (def: do not)
 	-E exitcode	force exit with exitcode (def: exit based on success or failure of the action)
 
-	[ignored]	all arguments are igoored
+	[ignored]	all arguments are ignored
 
 Exit codes:
      0         all OK