Only update documentation if the version has been released (i.e. a git
tag corresponding the version we're updating exists) or it is for the
master branch. Prevents us from pointing users to documentation of an
unreleased version.
Also updates github workflow to fetch full commit history (including
tags) so that git describe works correctly.
Add 'scripts/github/update-gh-pages.sh' for updating gh-pages branch.
This new script intended for github actions integration and builds the
html documentation from the currently checked-out commit and updates the
corresponding version subfolder in the gh-pages branch. The version is
taken from GITHUB_REF environment variable and defaults to 'master' if
the env var is empty. For testing purposes or manual updates the
subfolder can also be given directly as a command line argument.
Add 'scripts/test-infra/build-gh-pages.sh' for verifying that site
(gh-pages) builds successfully. This is intended for integration with
kubernetes test-infra.
Finally, add Github workflow for updating gh-pages. This job is run on
master and release branches plus all tags starting with letter 'v'.
