Patterns: Add descriptions to user-created patterns

[carolinan]

What problem does this address?

Pattern descriptions add important information for any user who is not able to see the blocks that are included in a pattern, or any user who needs the information in a different format than the preview.

There is no way for a user to add a description to user-created patterns.

What is your proposed solution?

Perhaps the excerpt field could be re-purposed as a description for this post type.

[richtabor]

I agree this could be nice, especially as patterns keep evolving.

Something like this:

[richtabor]

@youknowriad how would you see this best reconciling for patterns, related to the ongoing consolidation efforts in #57049

[youknowriad]

I'm going to be working on the excerpt field soon to show it similarly in site and post editors. If the post type supports excerpts then it will show up.

[youknowriad]

This PR #57096 adds the excerpt panel to the site editor. So if we enable excerpt support for wp_block post type as a follow-up, the panel will show up.

[richtabor]

So if we enable excerpt support for wp_block post type as a follow-up, the panel will show up.

@carolinan do you mind taking that? 🙇

[carolinan]

Adding the excerpt support is easy enough, but I found a bug with the Site Editor Pattern screen. There is a regression where there is no way for a screen-reader to actually read out the description to the user, no matter if "grid" or "list" is selected.

[richtabor]

Noting that this is supported now. The UI could be much better (it's not quite discoverable).