Support building of documentation for each stable release
We should support building multiple documentation versions (stable releases, master) and switching between them.
New jenkins job that takes a git ref (tag or 'master') and builds documentation for that version.
- git checkout target version
- build documentation
- parameter for target version, displayed on page header
- link to index page with all versions
- upload documentation to doc server at a target version directory
- regenerate index page with all versions + master
- upload index page
- documentation lists selected version, dropdown menu links to every version
- jenkins job to generate documentation for target version (either as part of build pipeline or release process)