Remove schema transformations from the concept of telemetry stability for now

[trask]

Fixes #3296
Fixes #2606

Changes

Prepares versioning-and-stability.md and telemetry-stability.md documents to be marked Stable themselves, by removing schema transformations from the concept of telemetry stability for now.

Note: I wasn't quite sure where to move the pieces that I removed, definitely open to feedback.

[lmolkova]

Also fixes #2606

[tigrannajaryan]

Prepares versioning-and-stability.md and telemetry-stability.md documents to be marked Stable themselves, by removing schema transformations from the concept of telemetry stability for now.

Note: I wasn't quite sure where to move the pieces that I removed, definitely open to feedback.

Why remove instead of marking the individual sections as "Experimental"?

[tigrannajaryan]

Blocking since I don't think we need to delete the text when we can instead mark the section "Experimental".

Happy to unblock this if we think the sections are wrong and do need to be removed, but that is not what the PR description says at the moment. In the past our approach about useful but not yet ready to make "Stable" sections of the spec was to label section stability individually.

[trask]

Why remove instead of marking the individual sections as "Experimental"?

some of the language was embedded into sections which we would otherwise want to mark stable

I will try to re-work the PR in a way that pulls that language out into separate sections instead of deleting

though let's resolve the new discussions going on in #3296 first, as that may affect the breakout as well

[trask]

closing in favor of #3380