Update Grouping and Order of Versions displayed on https://start.grails.org/

[jamesfredley]

This will likely need to wait on 7.0.0 when we have two releases with the workflows in the git release tag so they can be deployed. Or if we circle back and release 6.1.3.

possibly something like:

6.2.2 - default
6.1.2
------------
7.0.0-SNAPSHOT
6.2.3-SNAPSHOT
6.1.3-SNAPSHOT

Which by key is:

release - default
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[jamesfredley]

apache/grails-forge#380