CRI Implementation metadata

There is already a category for "container runtimes" which is great but is more generally scoped, it would be nice if there was some way to get a list specifically of CRI implementations, or runtimes that are CRI compatible. Not sure if this should be a new `implements CRI: true` field, or a category, or something else :) With the Dockershim deprecation, a lot of folks will want to see their options specifically re: CRI.

Start by examining how the existing "container runtimes" category and project metadata are represented in the landscape. Clarify whether CRI compatibility should be represented as a field, category, or another mechanism; done means users can identify and filter CRI-compatible runtime options.

Written by the indexing model from the issue text.