Fix action workflow definitions for external contributors

[stes]

• The documentation status workflow needs to be updated to the pull_request_target as it uses the GITHUB_TOKEN to run.
• For the docs workflow, since all repos are public, we removed the token in the checkout action which allows external contributors to run this workflow.

Close #32

[stes]

Seems like this runs now, just the comment (see #32 ) is missing. But checks pass, so I will merge this for now because it unblocks other open PRs.