[DOCS] 8.1.0 Release Notes

[nastasha-solomon]

Generate the 8.1.0 release notes.

For this release, which is publishing on March 1:

Steps to follow:

1. Check out the main branch.
2. Run a git fetch origin then git pull to pull in the latest changes.
3. Create a branch for the release notes, for example, issue-XXX-8.1.0-rn.
4. Add release notes to the 8.1 asciidoc file.
   NOTE: Might need to create this file if it's not yet been created.
5. Add an include to the release-notes.asciidoc file for the 8.1 release notes to update the release note's index page. The include should be: include::release-notes/8.1.asciidoc[]
6. Open a PR and switch the base branch (which is the PR will merge into) from 8.1 to main.
   NOTE: Make sure to add the correct labels. If the 8.2 branch is created before 8.1 GAs, will need to add the v8.2.0 label to ensure the RN is backported to the 8.2 branch.
7. Complete the technical and editorial review, then merge the PR to main.