Support for checkboxes

[Stanzilla]

Required Information

Entering this information will route you directly to the right team and expedite traction.

Question, Bug, or Feature?
Type: Feature

Should this get assigned to @damccorm?
Assign to damccorm: yes

Issue Description

Would love to way to act on the status of a checkbox being checked or not

[damccorm]

Hey, sorry this slipped through the cracks. This is actually doable today! Here's an example of where we're doing this with apache/beam - https://github.com/apache/beam/blob/ab5992940c1e3c1d004cfd40d8a087e1d6436f5e/.github/issue-rules.yml#L51

Basically, you can use - [ ] Content to detect an unchecked box and - [x] Content to detect a checked box.