Docs for server 4.6

[rosieyohannan]

Description

Preview here: https://internal.circleci.com/docs/server/latest/overview/circleci-server-overview/

• Create 4.6 docs set in latest directory. When 4.7 is released, 4.6 will be moved to the 4.6 directory and 4.7 will be put in latest.
• Add noindex: false to all server docs that aren't in latest to avoid duplication for SEO
• Updates for release
• Release notes for 4.6.0

Reasons

4.6 release

Content Checklist

Please follow our style when contributing to CircleCI docs. Our style guide is here: https://circleci.com/docs/style/style-guide-overview.

Please take a moment to check through the following items when submitting your PR (this is just a guide so will not be relevant for all PRs) 😸:

• [ ] Break up walls of text by adding paragraph breaks.
• [ ] Consider if the content could benefit from more structure, such as lists or tables, to make it easier to consume.
• [ ] Keep the title between 20 and 70 characters.
• [ ] Consider whether the content would benefit from more subsections (h2-h6 headings) to make it easier to consume.
• [ ] Check all headings h1-h6 are in sentence case (only first letter is capitalized).
• [ ] Is there a "Next steps" section at the end of the page giving the reader a clear path to what to read next?
• [ ] Include relevant backlinks to other CircleCI docs/pages.