Fix and clean up menu structure

[marians]

This PR fixes the menus and does a few more things

• config.yaml contained entries for pages. I removed those for the principal menu and specified the according data in the pages's front matter.
• Several pages did not appear in the menu. I added them by adding the front matter data under the menu: key.
• The content of page /overview/observability/logging/architecture/ moved up one level to /overview/observability/logging/, because there was no content on that node and the architecture page was the only one in the section.
• Adjusted some linkTitle to make the menu more readable

Before:

[marians]

This file shouldn't be in the repo

[github-actions]

This PR moves/renames or deletes some files. Please make sure to

• maintain references (also important for images)
• Maintain aliases in the front matter of moved markdown files

[lyind]

Not sure how to deal with empty descriptions without triggering the front-matter validator.

Otherwise LGTM