- update references to default branch name in docs, workflows
- use HEAD in github urls, which always works regardless of default branch name
- fix petstore URLs since the old petstore links seem to have stopped working
update several links (html targets don't work anymore)
had to add rest-api redirect so link would resolve,
since there isn't a ref for files in _static
In 0.8, the jupyterhub api token can also be used to make requests to
hte jupyter notebook given some conditions. This commit updates that
documentation
