Mention plugin.rnc in the docs

[stefan-jung]

There is a Relax NG schema (plugin.rnc) that can be used to validate plugin.xml files. This schema should be mentioned in the Plug-in configuration file topic.

[infotexture]

This one's been open for a while.

@xephon2 Could you submit a PR with information on how this is used?

[stefan-jung]

Raised PR #175

[infotexture]

Apart from the XML validation errors in #175, I don't think it's enough to just paste a codeblock that contains the .rnc reference.

I do think it makes sense to provide information on this file and how it is used, but that may be better provided in a separate section or topic on ”Validating plug-in descriptor files” (or similar).

So worth doing 👍, but will require a bit more effort.

We'd also need to clarify whether any other editors (apart from oXygen) provide the necessary XML Catalog entries to automatically validate files based on the Schema reference in the processing instruction:

<?xml-model href="dita-ot/plugin.rnc" type="application/relax-ng-compact-syntax"?>

For future reference: See dita-ot/dita-ot#1757 for background information and history.