Move observability docs to the new format

[QuentinBisson]

What this PR does / why we need it

This PR moves some of the existing docs and adjust them a bit under the new tutorials section. It also fixes a few issues with existing links.

I'm also using this to proposes adding a section about the observability platform in the changes section. I did not run the script to avoid adding too much changes in that PR. @Rotfuks could you take a look at those tutorials and see if we can improve them towards our observability platform journey?

Things to check/remember before submitting

• If you made content changes

  • Run make dev to render and proofread content changes locally.
  • Bump last_review_date in the front matter header if you reviewed the entire page.

[pipo02mix]

I have pushed some fixes to fix vale checks

[pipo02mix]

@Rotfuks do you have a chance to look at this?

[QuentinBisson]

@pipo02mix I think we're only blocked by failing links now. did you move some files over?