fix typo in readme.

[baikai]

Description of your changes

Checklist

I have:

• [x] Run make reviewable to ensure this PR is ready for review.
• [x] Ensured this PR contains a neat, self documenting set of commits.
• [x] Updated any relevant documentation, examples, or release notes.
• [x] Updated the dependencies in app.yaml to include any new role permissions.
• [x] Updated the package resources documentation to include any new managed resources or classes.

[wonderflow]

Try fix CI by:

make reviewable

git commit -s --amend

[baikai]

@hasheddan thx, it's ok for me.