Rename and redirect AM.1.01 and remove the redundant title heading.

This makes a few changes to and for AM.1.01 in accordance with the URL guidance in our general Writing Style Guidelines and the heading guidance in our Handbook Style Guide.

1. It replaces all uppercase letters in the file name with their lowercase counterparts.
2. It replaces all underscores in the file name with hyphens.
3. It removes the redundant level-1 heading (level-1 headings are auto-generated from the "title" properties in the frontmatter).
4. It updates internal links to use the new URL.
5. It adds a redirection rule to redirects.yml to handle requests for the old URL from cached pages, our on-page search system (which takes a while to include changes), bookmarks, and external links.

Note: This Merge Request is part of a campaign tracked with Issue #5982 (closed).