Update docs to support OTEL GA

[JStickler]

What this PR does / why we need it:
Updating the docs in advance of OTEL release to remove "experimental" notes.

Also restructured release notes so that most recent content is first.

[JordanRushing]

LGTM

[grafanabot]

The backport to release-2.9.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-11858-to-release-2.9.x origin/release-2.9.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 46c6118eb2a2d56406042431dfbed288df6e924b

When the conflicts are resolved, stage and commit the changes:

git add . && git cherry-pick --continue

If you have the GitHub CLI installed:

# Push the branch to GitHub:
git push --set-upstream origin backport-11858-to-release-2.9.x
# Create the PR body template
PR_BODY=$(gh pr view 11858 --json body --template 'Backport 46c6118eb2a2d56406042431dfbed288df6e924b from #11858{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title "[release-2.9.x] Update docs to support OTEL GA" --body-file - --label "size/S" --label "type/docs" --label "backport" --base release-2.9.x --milestone release-2.9.x --web

Or, if you don't have the GitHub CLI installed (we recommend you install it!):

# Push the branch to GitHub:
git push --set-upstream origin backport-11858-to-release-2.9.x

# Create a pull request where the `base` branch is `release-2.9.x` and the `compare`/`head` branch is `backport-11858-to-release-2.9.x`.

# Remove the local backport branch
git switch main
git branch -D backport-11858-to-release-2.9.x