Bring back misspelling redirection for docs

The old TrollTech doc site would offer suggestions if you misspelt something. E.g. if you requested doc/qstrang.html the redirect page would provide a link to qstring.html . The same thing occurred for doc/qstring.htm . Since the docs are sometimes used as a reference by people typing in the direct URL, it would be nice to have these redirection links back for one-edit-distance mispellings.