docs(alert): clarify remote rule evaluation

[LukoJy3D]

What this PR does / why we need it:

When scrolling alerting documentation, ruler remote evaluation is not mentioned, and for me, it solved many issues, so it would be great to have it in alerting docs.

Which issue(s) this PR fixes:
Fixes #14441

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[JStickler]

[docs team] LGTM, thanks for taking the time to update the docs.

[loki-gh-app]

The backport to release-3.0.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-14481-to-release-3.0.x origin/release-3.0.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x d63fbeddff238bffdf0abd8866a582049ea37058

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-14481-to-release-3.0.x
# Create the PR body template
PR_BODY=$(gh pr view 14481 --json body --template 'Backport d63fbeddff238bffdf0abd8866a582049ea37058 from #14481{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title 'docs(alert): clarify remote rule evaluation (backport release-3.0.x)' --body-file - --label 'size/M' --label 'type/docs' --label 'backport' --base release-3.0.x --milestone release-3.0.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-14481-to-release-3.0.x

# Create a pull request where the `base` branch is `release-3.0.x` and the `compare`/`head` branch is `backport-14481-to-release-3.0.x`.

# Remove the local backport branch
git switch main
git branch -D backport-14481-to-release-3.0.x