Remove authors#create_toc action

[damisul]

It seems to me this method is outdated and not used now (we have to_manual_toc instead). Moreover it lacks permissions check, so it is available to anyone.

Also, if we'll decide to remove it we probably can also remove toc_template constant from constants.yml

WDYT, @abartov

[abartov]

Yes, this code can be removed.