Remove strong typedef from comparisons page.

Typedef is going away and is already deprecated, no reason to keep it in the docs. Note that the page lists language features and not library features so I'm leaving out `Typedef` from Phobos.

Also the "contact me" is unnecessary, we have the "improve me" button.

I'm working page-by-page so I'll remove typedef from other pages with separate pull requests (this will also avoid rebase problems).