fix indentation for FAQ 10.6.1, update sitemap

We indent FAQ 10.6.1, added in a previous commit, in the
same way we indent 3rd level FAQ numbers.  Also adjusted
the vertical whitespace around the FAQ in `faq.md` to
be consistent with the other FAQ sections.

Updated sitemap.

Ran `make faq sitemap` to perform the above.

faq.html

@@ -592,8 +592,10 @@
 <li><strong>Q 10.3</strong>: <a class="normal" href="#dot_files"> What is the purpose of the <code>.top</code>, <code>.allyear</code>, <code>.year</code> and <code>.path</code> files?</a></li>
 <li><strong>Q 10.4</strong>: <a class="normal" href="#terms"> What is the current meaning of the IOCCC terms Author, Entry, and Submission?</a></li>
 <li><strong>Q 10.5</strong>: <a class="normal" href="#licence">Am I allowed to use IOCCC content?</a></li>
-<li><strong>Q 10.6</strong>: <a class="normal" href="#try_mastodon">What is Mastodon and why does the IOCCC use it?</a></li>
+<li><strong>Q 10.6</strong>: <a class="normal" href="#try_mastodon">What is Mastodon and why does the IOCCC use it?</a>
+<ul>
 <li><strong>Q 10.6.1</strong>: <a class="normal" href="#mastodon_notifications">How can I get push notifications when the judges post something on mastodon?</a></li>
+</ul></li>
 <li><strong>Q 10.7</strong>: <a class="normal" href="#tabstops">How do I set certain tabstops for viewing source code in vi(m)?</a></li>
 <li><strong>Q 10.8</strong>: <a class="normal" href="#menus">How do the menus on the website work and what can I do if they don’t work?</a></li>
 <li><strong>Q 10.9</strong>: <a class="normal" href="#author-information">How do I find more information about a winning author of an entry?</a></li>