Avoid hard-coding 5.x prefix

Author: marcphilipp

RELEASING.md

@@ -27,14 +27,14 @@
 - [ ] Fast-forward merge the release branch to `main` and push to GitHub
 - [ ] Create release notes for the next preview or feature release from the template
 
-### Feature releases (5.x.0)
+### Feature releases (x.y.0)
 
 - [ ] Fast-forward merge the release branch to `main` and push to GitHub
 - [ ] Update the [security policy](https://github.com/junit-team/junit5/blob/main/SECURITY.md) and commit with message "Update security policy to reflect 5.x release" or similar
 - [ ] Create release notes for the next feature release from the template
 - [ ] Update [JBang catalog](https://github.com/junit-team/jbang-catalog/blob/main/jbang-catalog.json)
 
-### Patch releases (5.x.y)
+### Patch releases (x.y.z)
 
 - [ ] Cherry-pick the tagged commit from the release branch to `main` and resolve the conflict in `gradle.properties` by choosing the version of the `main` branch
 - [ ] Include the release notes of the patch release on `main` if not already present