Improve CRD docs

Author: sbernauer

crates/stackable-operator/crds/DummyCluster.yaml

@@ -639,6 +639,8 @@ spec:
                 description: |-
                   A list of generic Kubernetes objects, which are merged onto the objects that the operator
                   creates.
+
+                  List entries are arbitrary YAML objects, which need to be valid Kubernetes objects.
                 items:
                   type: object
                   x-kubernetes-preserve-unknown-fields: true

crates/stackable-operator/src/patchinator/crd.rs

@@ -10,6 +10,8 @@ pub struct ObjectOverrides {
     /// A list of generic Kubernetes objects, which are merged onto the objects that the operator
     /// creates.
     ///
+    /// List entries are arbitrary YAML objects, which need to be valid Kubernetes objects.
+    //
     // TODO: Add link to concepts page once it exists
     #[serde(default)]
     #[schemars(schema_with = "raw_object_list_schema")]