Update feature gate / stability notes in documentation

Author: jpbetz

content/en/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions.md

@@ -1686,9 +1686,7 @@ may also be used with field selectors when included in the `spec.versions[*].sel
 {{< feature-state feature_gate_name="CustomResourceFieldSelectors" >}}
 
 For Kubernetes {{< skew currentVersion >}} the ability to define field selectors for
-custom resources is available by default (enabled by default since Kubernetes v1.31);
-you can disable it for your cluster  by turning off the `CustomResourceFieldSelectors`
-[feature gate](/docs/reference/command-line-tools-reference/feature-gates/).
+custom resources is a stable feature since Kubernetes v1.32.
 The `spec.versions[*].selectableFields` field of a {{< glossary_tooltip term_id="CustomResourceDefinition" text="CustomResourceDefinition" >}} may be used to
 declare which other fields in a custom resource may be used in field selectors
 with the feature of `CustomResourceFieldSelectors`