Update Documentation Workflow's Header Comments

[surlymoor]

As of right now, docs.yml still mentions adrdox.

# Builds the documentation, with the latest adrdox, with every push to master,
# and deploys it to the gh-pages branch. Derived from Paul Backus'
# https://github.com/pbackus/sumtype/blob/master/.github/workflows/docs.yml.

The whole thing should probably just be truncated to state the file's origins since the workflow is straightforward (for now) and has comments where needed.

[schveiguy]

Yep, thanks! I will fix this when I get a chance.