Add io.moderne as root category, same as org.openrewrite

[timtebeek]

Anything in particular you'd like reviewers to focus on?

We already had io there, but then we also have both org and org.openrewrite. Would this then similarly help group recipes? as needed for

• Fix categorization for Moderne recipes rewrite-recipe-markdown-generator#167

Any additional context

• https://github.com/moderneinc/rewrite-ai-search/commit/76df9fb37d57791f0e86e9d5eb1f0b46878045f1