Allow opting-out of username links in release notes

[lilnasy]

This PR adds a config to @changesets/changelog-github to remove links from GitHub usernames, allowing contributors to appear prominently in releases in the "Contributors" section.

To make use of this feature, set linkUsernames to false in your .changeset/config.json file:

{
    "$schema": "https://unpkg.com/@changesets/config@1.7.0/schema.json",
    "changelog": [
        "@changesets/changelog-github",
        {
            "repo": "your-org/your-repo",
+           "linkUsernames": false
        }
    ]
}

See GitHub documentation for more details.

[changeset-bot]

🦋 Changeset detected

Latest commit: ec71a9a

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

This PR includes changesets to release 1 package

Name	Type
@changesets/changelog-github	Minor

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[Andarist]

I just wonder if we shouldn't transform the release notes and unlinkify those there. The downside of the proposed approach here is that the generated markdown won't have those links in it. GitHub doesn't automatically linkify those mentions in markdown files

[lilnasy]

I was under the impression that the getReleaseLine function would only be ised for releases not changelog. I agree CHANGELOG.md does not need to change. I will look into your suggestion.

[Andarist]

Those are called to generate the CHANGELOG entries and the latest update is extracted by this function. So to do what I suggested you'd have to transform the extracted content there