PR authors use canonical guidance without repository templates

.github/CONTRIBUTING.md

@@ -2,3 +2,10 @@
 
 Follow the guidance in the central [MSX documentation](https://msx.no/docs/)
 when contributing to this repo.
+
+Write pull request descriptions using the canonical
+[MSX PR Format](https://msx.no/docs/Ways-of-Working/PR-Format/) instructions.
+Use its
+[complete description example](https://msx.no/docs/Ways-of-Working/PR-Format/#complete-description-example)
+for the actual PR record. Do not add or copy GitHub PR-template files; follow the
+[Repository Standard's file policy](https://msx.no/docs/Ways-of-Working/Repository-Standard/#no-pr-template-files).

README.md

@@ -5,8 +5,19 @@ community defaults. GitHub uses these files when an MSX repository does not
 define its own corresponding file. This repository must remain public for the
 fallback behavior to work.
 
+This repository is for MSX repository maintainers and contributors.
+Maintainers use GitHub's community-file fallback to share organization guidance.
+Contributors use canonical MSX instructions to write pull request descriptions on GitHub.
+
 The central [MSX documentation](https://msx.no/docs/) is the source for MSX
 standards and ways of working.
 
 Shared MSX images and editable artwork are available in the [media](media)
 folder.
+
+Pull request authors use the canonical
+[MSX PR Format](https://msx.no/docs/Ways-of-Working/PR-Format/) instructions.
+This repository provides no local or organization-fallback PR-template files,
+following the
+[Repository Standard's file policy](https://msx.no/docs/Ways-of-Working/Repository-Standard/#no-pr-template-files).
+The format stays in canonical documentation, not repository template files.