[google_sign_in] fix registration links

[kevmoo]

Fixes flutter/flutter#81847

[stuartmorgan-g]

Most users are reading the README from pub.dev, so this needs a version and CHANGELOG update so we can publish it.

Also, we don't usually strictly enforce an 80-char limit for .md files; is there a reason you've reformatted the whole file?

[kevmoo]

Most users are reading the README from pub.dev, so this needs a version and CHANGELOG update so we can publish it.

Also, we don't usually strictly enforce an 80-char limit for .md files; is there a reason you've reformatted the whole file?

Updated changelog. I was hoping to bump the example, too – before this is published.

RE formatting: my editor does that for me. I find it easier to read. I also cleaned out some bits at the bottom.

Happy to revert unrelated changes if you prefer.

[stuartmorgan-g]

LGTM

[fluttergithubbot]

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[stuartmorgan-g]

• This commit has empty status or empty checks. Please check the Google CLA status is present and Flutter Dashboard application has multiple checks.

Weird. I have no idea what this means.