Add anchors to the mobile page to better navigate

The page at https://tb-manual.torproject.org/mobile-tor/ is becoming too big, has many different aspects of TBA. A table of contents with anchors to the different headings would be good, also adding such headers.

For example for the Troubleshooting version, to have a link like https://tb-manual.torproject.org/mobile-tor/#troubleshooting , you can add

<a name="troubleshooting"/>

Just on top of the Troubleshooting heading.

Same with Known Issues, etc.

This links are also good for SEO

This could be automated with the lektor-markdown-headings plugin