docs: Remind release cutters about crd-ref-release

Same kind of reminder comment that crd-docs-version has, in case the
attribute is ever edited by hand instead of via the release script.

Author: lfrancke

antora.yml

@@ -30,6 +30,8 @@ asciidoc:
     # The CRD reference on the Stackable Hub. crd-ref links the listing;
     # deep links follow {crd-ref}/<group>/<apiVersion>/<kind>{crd-ref-release}
     crd-ref: "https://hub.stackable.tech/crds"
+    # Keep this in line with the 'version' key above: '?release=dev' on main,
+    # '?release=<major.minor>' on release branches (the release script sets it).
     crd-ref-release: "?release=dev"
     # DEPRECATED: the old CRD browser attributes below are still used by the
     # operator docs; they migrate to crd-ref repo by repo (operator sweep).