Add Signal Icon

[MiahaCybersec]

What does this PR Change?

• Adds Signal Icon

While this does not address an existing issue, Signal recently added support for usernames, which will benefit those that use the Starlight theme and wish to publicly link their Signal profile.

This is technically a duplicate of #1779, but I closed that pull request and created this one to comply with contributor guidelines.

[changeset-bot]

🦋 Changeset detected

Latest commit: 07d641f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@astrojs/starlight	Patch

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Name	Status	Preview	Updated (UTC)
starlight	✅ Ready (Inspect)	Visit Preview	Apr 30, 2024 2:55pm

[HiDeoo]

Thanks for your contribution 🙌

This is looking really great. I left a few suggestions but very minor ones. 👍

[HiDeoo]

Just noticed that a label is missing for the new entry (used by screen readers) but I cannot suggest a change for it as it's outside of the review range.

It's around line 71 and would look close to something like:

  openCollective: 'Open Collective',
+ signal: 'Signal',

[MiahaCybersec]

Good catch, I completely missed that. It should be added now.

[HiDeoo]

Thanks for the update, this is looking perfect to me 👍

I also updated a test snapshot, did not remember we had one for socials (I wonder if we should make this one a bit more lenient so we do not have to update it every time we add a new social network).

Note that this won't be merged until the next patch release, as this would update the Starlight documentation and we do not want to do that before the icon is actually available to users.