Change the title of if statement in trpl book.

[loganchien]

Slightly change the title to make it look more consistent with other chapters (e.g. Match.)

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @steveklabnik (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see CONTRIBUTING.md for more information.

[steveklabnik]

Actually, it should be the other way around. Care to fix match instead?

[steveklabnik]

(and thank you!)

[loganchien]

However, unfortunately, it seems that the backticks do not work in the title block of pandoc. Unlike the backticks in the headings, the backticks in the title block will be left as-is (and won't be changed to the <code></code> tags.) Is this the preferred result?

[steveklabnik]

Ugh. No. :(

I guess this patch works, then. Thank you!

[steveklabnik]

@bors: r+ 8c3d914

[aturon]

@bors: rollup