Validation: Fix multiple issues

[annmariehitchcock]

This PR addresses the following issues: docs-link-absolute image-alt-text-duplicated ms-author-invalid description-missing duplicate-descriptions

There are build warnings, but we were instructed not to fix duplicate title or H1 issues.

[annmariehitchcock]

Global effort to fix validation errors

@Rick-Anderson @mcleblanc

The Content & Learning team is fixing build validation errors on docs.microsoft.com. This effort will eliminate potential accessibility, security, and usability issues. This PR includes only build validation fixes and does not change other content. I’d very much appreciate your timely review and feedback on these changes I’ve suggested. Thanks!

[tfosmark]

@annmariehitchcock Please address the merge conflicts. Thanks!

[annmariehitchcock]

Merge conflict was addressed. Thank you!

[v-emilypr]

#please-close