fix(docs-site): style custom announcement bar

[jeffmerrick]

The docusaurus version update changed the class names on the announcement bar which broke the custom styles for it. Adjusting the selector brought back the styles. Also updated the link url while I was in there.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[github-actions]

Unit Test Results (build & test)

562 tests   562 ✔️  12m 50s ⏱️
139 suites      0 💤
139 files        0 ❌

Results for commit 285ecea.

♻️ This comment has been updated with latest results.

[hsheth2]

Thanks @jeffmerrick - it mostly looks good, but the announcement bar seems to cover the search bar on mobile

[jeffmerrick]

@hsheth2 Added a fix! It was covering the mobile nav too. Looks like the official Docusaurus docs have the same bug.

[shirshanka]

LGTM

[hsheth2]

Thanks Jeff!