Fix/hookdoc generation

[helen]

Description of the Change

Add/flesh out hook docs so they can be picked up by the page generator. IMPORTANT NOTE: This PR also changes the action to run on develop instead of just master; once this is confirmed to be working we should switch it back to master so hook docs don't update separately from releases.

Alternate Designs

n/a

Benefits

Actual hook docs at https://10up.github.io/classifai/

Possible Drawbacks

n/a

Verification Process

Ran npm run build:docs locally and checked every single hook doc page.

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

See #189

Changelog Entry

n/a

[jeffpaul]

looks good to me, thanks!