Global Styles: Update Block specific CSS label to include additional instructions.

[jordesign]

What?

This PR adds an additional sentence of text to the label for Block specific 'Additional CSS' in the Styles panel (Styles > Block > Paragraph > Additional CSS).

This sentence provides context and instructions for the formatting of the CSS when it is in this mode (specific to a certain block type).

Why?

Addresses part of #49531 - providing additional details of how to use the CSS panel in this context.

How?

Adds an additional bit of information to the label - to guide the user.

Testing Instructions

1. Open the Site Editor and edit a template
2. Open the styles panel and go to Blocks > Paragraph (or another block) > Additional CSS.

Screenshots or screencast

[jordesign]

I'd be willing to expect the exact wording of the additional text could be reviewed and improved.

[annezazu]

Adding needs copy review as I agree that this could be refined a bit! Thanks for opening either way 💥

[provenself]

Sorry—just fixed our Github notification settings, so only seeing this now! Copy looks fine, but if there's any interest, I think we could do a minor tweak:

Add your own CSS to customize the appearance of the %s block. You do not need to include a CSS selector, only the property and value.

[kristastevens]

Hello @jordesign! Can we get the "Needs Copy Review" label removed here? This GH issue keeps popping up in our Slack channel and we've satisfied it. (I tried to figure out how to remove the label myself, but I don't seem to have the option of doing so.) Thanks so much!

[jordesign]

@kristastevens - sure can! Sorry about that.

[kristastevens]

No worries at all! Thanks so much, friend!

[apeatling]

@jordesign Are you able to rebase this one? If not I can help assuming this is still relevant.

[jordesign]

Hey @apeatling have updated this one - as it turns out the structure/location of that string needed to change anyway since I first issued this PR.

Fingers crossed - it should be good to go now.

[apeatling]

Looks good, I'm re-running the tests since they didn't pass and it seems unrelated to this PR.

[jordesign]

@apeatling Looks like it is still failing on some kind of linting error I can't figure out I'm afraid :)
https://github.com/WordPress/gutenberg/actions/runs/6193057817/job/16834334818?pr=49626

[apeatling]

Turns out it was the double space in the string causing it to fail. Took a little while to track down. 😅

[jordesign]

Awesome - thanks so much for sorting that out :)