docs: Update approx_topk documentation

[09jvilla]

Added a little more content to how the approx_topk works that was previously only in the release notes.

Please backport to Loki 3.3 docs when complete.

[09jvilla]

@jeschkies -- Can we get a review for technical accuracy when you have a chance? Some of this was in the release notes but felt more appropriate in the LogQL docs.

[github-actions]

💻 Deploy preview deleted.

[JStickler]

[docs team] I think we still want to mention that we're talking about the top 1,000 elements, but other than that, looks good.

[09jvilla]

@jeschkies , re-requesting a review now that I incorporated your feedback! Let me know.

[loki-gh-app]

The backport to release-3.1.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-16223-to-release-3.1.x origin/release-3.1.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 541e93c157721a0634254b1846ad0f214f8f36df

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-16223-to-release-3.1.x
# Create the PR body template
PR_BODY=$(gh pr view 16223 --json body --template 'Backport 541e93c157721a0634254b1846ad0f214f8f36df from #16223{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title 'docs: Update `approx_topk` documentation (backport release-3.1.x)' --body-file - --label 'size/S' --label 'type/docs' --label 'backport' --base release-3.1.x --milestone release-3.1.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-16223-to-release-3.1.x

# Create a pull request where the `base` branch is `release-3.1.x` and the `compare`/`head` branch is `backport-16223-to-release-3.1.x`.

# Remove the local backport branch
git switch main
git branch -D backport-16223-to-release-3.1.x

[loki-gh-app]

The backport to release-3.2.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-16223-to-release-3.2.x origin/release-3.2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x 541e93c157721a0634254b1846ad0f214f8f36df

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-16223-to-release-3.2.x
# Create the PR body template
PR_BODY=$(gh pr view 16223 --json body --template 'Backport 541e93c157721a0634254b1846ad0f214f8f36df from #16223{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title 'docs: Update `approx_topk` documentation (backport release-3.2.x)' --body-file - --label 'size/S' --label 'type/docs' --label 'backport' --base release-3.2.x --milestone release-3.2.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-16223-to-release-3.2.x

# Create a pull request where the `base` branch is `release-3.2.x` and the `compare`/`head` branch is `backport-16223-to-release-3.2.x`.

# Remove the local backport branch
git switch main
git branch -D backport-16223-to-release-3.2.x

[09jvilla]

Julie, thanks for helping me get this released!