Community stewardship: Content updates

[dontlaugh]

Apart from infrastructure concerns (DNS, hosting), we need to update website content to reflect community stewardship of cro projects.

1. Change github links to Raku/cro-website
2. Remove "Training and Support"
3. Find a way to mention the historical origins of the project
   • Initial development by Edument
4. Update copyright to Raku Community
5. Update default branch in this site to main; make a commit indicating transfer to community stewardship

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Related issues:

• https://github.com/Raku/infra/issues/51

[dontlaugh]

At some point I would like this issue (or the website itself) to link to a steering committee issue/document/minutes that documents the transfer of responsibility.

I think we should continue development of the website under the Raku GitHub namespace, since it simplifies organization management. But I will assist in whatever leadership decides. :)