add "On the 'Activate your license' page" in 02-activation.mdx

[anatawa12]

Changes

• add "On the 'Activate your license' page" in 02-activation.mdx

https://github.com/game-ci/documentation/issues/408#issuecomment-1713127374

Checklist

• [c] Read the contribution guide and accept the code of conduct
• [x] Readme (updated or not needed)
• [x] Tests (added, updated or not needed)

[github-actions[bot]]

[anatawa12]

I have fixed the lint error