Tip: Review these changes grouped by change (recommended for most PRs), or grouped by feature (for large PRs).

@caugner I already mentioned 3 examples (css.properties.gap.flex_context and css.properties.gap.grid_context, and html.global_attributes.inert.ignores_find_in_page) and mention more specific guidelines (e.g., secure_context_required). Do you have something in mind here?

We discussed this on a special double-length BCD call today. Main takeaways:

• This could use some improved wording (e.g., "readily" needs to be made more simple). I'll do this soon.

• Reviewing past practice could help reviewers here. What do existing behavioral subfeatures look like? I said I'd try to generate a spreadsheet that lists the behavioral subfeatures.

• It's hard to review existing behavioral subfeatures because they're hard to find. We discussed the idea of adding an (internal, at least to start) field like type: "behavior" to make it easier to find these features and lint certain aspects of them (for example, to require a description for all behavioral subfeatures).

This came up again on today's BCD call. I've made a few small changes:

• Added text requiring a description.
• Added links to all more-specific behavioral subfeature guidelines.
• Added "feedback welcome" text at the top of the guideline. In today's call, we talked about adopting the guideline with the understanding it's sort of provisional. We talked about removing this text in 6 months (assuming the guideline survives that long).
• Added this guideline to docs index.

@caugner and @Elchi3, I'd welcome re-review here. Thank you!

From today's BCD call: this still needs a link to this PR, for symmetry with other guidelines. I'll try to get to this shortly.