Fix issue #1720 text and token-help inconsistencies

> [!CAUTION]
> Protected files were modified in this change.
> This pull request is in `request_review` mode and requires explicit human scrutiny before merge.
>
> Protected files: `README.md`

## Summary

This PR resolves issue #1720 by fixing the reported user-facing text defects:

- Corrected README formatting so `## License` renders as a proper heading (added the missing newline).
- Clarified token help text in `scripts/fetch-workflow-logs.py` to explicitly state the token is used for API authentication.

## Files changed

- `README.md`
- `scripts/fetch-workflow-logs.py`

Closes \#1720.

---
[What is this?](https://ela.st/github-ai-tools) | [From workflow: Trigger Text Auditor](https://github.com/elastic/ai-github-actions/actions/runs/30547656886)

Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not.

---

> [!NOTE]
> This was originally intended as a pull request, but the git push operation failed.
>
> **Original error:** pushSignedCommits: refusing unsigned push for branch 'fix-issue-1720-text-cleanups-1a860dcf66c6f857': Signed-commit payload violates file-protection policy (request_review): README.md
>
> **Workflow Run:** [View run details and download bundle artifact](https://github.com/elastic/ai-github-actions/actions/runs/30547656886)
>
> The bundle file is available in the `agent` artifact in the workflow run linked above.

To create a pull request with the changes:

```sh
# Download the artifact from the workflow run
gh run download 30547656886 -n agent -D /tmp/agent-30547656886

# Fetch the bundle into a temporary ref, then update the local branch
git fetch /tmp/agent-30547656886/aw-fix-issue-1720-text-cleanups.bundle refs/heads/fix-issue-1720-text-cleanups:refs/bundles/create-pr-fix-issue-1720-text-cleanups-1a860dcf66c6f857-f46133d0
git update-ref refs/heads/fix-issue-1720-text-cleanups-1a860dcf66c6f857 refs/bundles/create-pr-fix-issue-1720-text-cleanups-1a860dcf66c6f857-f46133d0
git checkout fix-issue-1720-text-cleanups-1a860dcf66c6f857
# Ensure the working tree matches the updated branch
git reset --hard
# Remove the temporary bundle ref
git update-ref -d refs/bundles/create-pr-fix-issue-1720-text-cleanups-1a860dcf66c6f857-f46133d0

# Push the branch to origin
git push origin fix-issue-1720-text-cleanups-1a860dcf66c6f857

# Create the pull request
gh pr create --title 'Fix issue #1720 text and token-help inconsistencies' --base main --head fix-issue-1720-text-cleanups-1a860dcf66c6f857 --repo elastic/ai-github-actions
```

Start by reviewing README.md and scripts/fetch-workflow-logs.py, the two files named in the issue. Check the reported heading formatting and token-help wording, then verify the resulting text renders and reads as intended; the issue is done when both user-facing defects are corrected.】【。

Written by the indexing model from the issue text.