docs: add missing h1 to page for skip to main content on home page

[bencodezen]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: #53015

What is the new behavior?

Currently the skip-to-content button does not have an h1 element to jump to, so this PR should add a proper anchor for the skip to main content element.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[github-actions]

Deployed adev-preview for 4135ae9 to: https://ng-dev-previews-fw--pr-angular-angular-55052-adev-prev-b0dvpu9q.web.app

Note: As new commits are pushed to this pull request, this link is updated after the preview is rebuilt.

[JeanMeche]

Clicking on the "skip to main button" still doesn't do anything for me with this change.

[bencodezen]

@JeanMeche Forgot to push another change. Let me know if it's still not working on your end!

[JeanMeche]

LGTM

[atscott]

This PR was merged into the repository by commit d63706e.

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