Add reference to CodeMeta

[mkuzak]

CodeMetaProject defines structured metadata, that can be used to describe software project. CODEMETA.json file can be created with by hand or with use of the online tool Create a CodeMeta file

[orchid00]

@mkuzak there are two places where codemeta is listed

_episodes/05-use-registry.md
checklist.md

[mkuzak]

Yes and I thought we could add a bit more to that.