Enable "Edit on GitHub" in more pages

[psiinon]

Enable on:

• FAQs
• Guides
• User Guide (requires changes in help converter)
• Blog posts
• ?

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How about we add a link (in the footer maybe?) to the relevant github file so people can easily suggest changes?
Hopefully these can be automated, but in some cases (like the evangelists) we'd need to add manual links to the relevant data files.

[thc202]

Updated to track other pages that should have this.