Create mkdocs.yml to auto build and upload docs artifact

[klosing]

Create a workflow to automatically build a new mkdocs site on changes and upload the artifact. Ideally we would want to use github pages to host this. As this requires us to either make the repo public, an enterprise account or to move the repo into a private non-organization repo of a pro user, we should check with Sven on this.

[klosing]

This now works as follows:

• Builds documentation for doc changes on:
  • A push to main
  • A pull request targeting main is created/updated
  • A Manual Trigger
• Deploys the documentation to github pages when:
  • A build was triggered on the main branch (by any of the above triggers)

There will be one artifact per unique pull request (This artifact gets overwritten by updates to the PR), as well as one artifact for the main branch (This is the artifact that is deployed on github pages).

This is ready for review/merge. After merge I will create a branch ruleset making a positive workflow status check mandatory for merges into main.