]DOC] Tempo 2.7 release notes

[knylander-grafana]

What this PR does:
Creates release notes for Tempo 2.7.

Which issue(s) this PR fixes:
Fixes ##4520

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[knylander-grafana]

Need the blog post link when it's ready.

[knylander-grafana]

If we do a video, we should add it here.

[github-actions]

This PR must be merged before a backport PR will be created.

[joe-elliott]

couple o thoughts, but basically looks good

[github-actions]

The backport to release-v2.7 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-4537-to-release-v2.7 origin/release-v2.7
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 8d2eb8e6a1c005fa0d25ec105c919e9171e92cbb

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-4537-to-release-v2.7
# Create the PR body template
PR_BODY=$(gh pr view 4537 --json body --template 'Backport 8d2eb8e6a1c005fa0d25ec105c919e9171e92cbb from #4537{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title '[release-v2.7] ]DOC] Tempo 2.7 release notes' --body-file - --label 'type/docs' --label 'backport' --base release-v2.7 --milestone release-v2.7 --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-4537-to-release-v2.7

# Create a pull request where the `base` branch is `release-v2.7` and the `compare`/`head` branch is `backport-4537-to-release-v2.7`.

# Remove the local backport branch
git switch main
git branch -D backport-4537-to-release-v2.7