Add guidelines for repository inclusion

repositories.md

@@ -0,0 +1,29 @@
+# Repositories on github.com/solid
+The [Solid GitHub organisation](https://github.com/solid/)
+contains repositories that are managed by the [Solid Team](https://github.com/solid/team/),
+covering the Solid specification and its processes and artifacts,
+and public communication on the Solid project.
+
+This document describes which repositories belong under _github.com/solid_,
+and which repositories belong elsewhere.
+This also pertains to other resources associated with those repositories,
+such as Gitter chat channels bearing the same name.
+
+## Repositories that are part of github.com/solid
+Repositories under github.com/solid need to satisfy the condition that:
+- their contents are managed by either:
+  - the [Solid administrators](https://github.com/solid/process/blob/main/administrators.md)
+  - the [Solid creators](https://github.com/solid/process/blob/main/creators.md)
+  - the [Solid editors](https://github.com/solid/process/blob/main/editors.md)
+
+Additionally, they need to satisfy one or more of the following conditions:
+- they are specification documents
+- they are documents related to processes for advancing the specification
+- they are guidelines or working documents for people within the Solid community
+- they are materials for Solid project websites (such as [solidproject.org](https://solidproject.org/))
+
+## Repositories that are not part of github.com/solid
+Repositories that satisfy one or more of the conditions below
+belong in other GitHub organisations or on other third-party places:
+- they are not managed by Solid administrators, creators, or editors
+- they are specific specification implementations or program code (that is not contributing to the display of the documents listed above)