Docs: Add GKS Think Tank information to the Getting Involved Page

[DanielPuthawala]

Feature description

In order to reduce the barrier to getting involved with Cat-VRS and spec development, we have been encouraging folks to join us at GKS think tanks, where we often have Cat-VRS issues under discussion. This should be reflected in our Getting Involved ReadTheDocs page.

Contribution

None

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GA4-4341