The structure looks like a nice improvement. I like it! What about removing dist-git from the the test section names?

• Generic Tests
• STI Tests
• tmt Tests

From "branding" point of view tmt should be always lowercase ;-)

I probably liked Guides a little bit more than How to but that might be just my personal preference. One more brainstorm idea: How about joining the Architecture section with this one?

• Pull Requests
• Gating
• Manifesto
• Onboarding...

I think content of both Gating and Manifesto could be considered as guide/how to as well. Just my two cents.

Updated.

I removed the Architecture and How-to sections altogether and moved the content one level up.

I think once we start splitting up and updating the content we can introduce those sections again. But for now it seems we can just put them on top for visibility.

I removed the Architecture and How-to sections altogether and moved the content one level up.

Makes sense, looks good.

Perhaps, since there's just a single page about tmt tests, there's no need of the extra sub-section, let's make the second level menu directly point to it:

** xref:tmt.adoc[tmt tests]

Otherwise looks good. Just wonder, why have you added the extra level to all pipeline headings?