Add social icon for Signal

[proprietary]

Signal added support for usernames and links. So it seems likely people will want to add an icon to their sites.

The icon in the SVG is a derivative of this:

https://commons.wikimedia.org/wiki/File:Signal-Logo.svg

which is in the public domain and/or has a permissive license.

This is what it looks like:

What does this PR change? What problem does it solve?

It just adds a SVG icon for Signal.

Was the change discussed in an issue or in the Discussions before?

No

PR Checklist

• This change adds/updates translations and I have used the template present here.
• I have enabled maintainer edits for this PR.
• I have verified that the code works as described/as intended.
• This change adds a Social Icon which has a permissive license to use it.
• This change does not include any CDN resources/links.
• This change does not include any unrelated scripts such as bash and python scripts.
• This change updates the overridden internal templates from HUGO's repository.

[adityatelange]

LGTM 👍

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud