add enum for rotationPolicy

Signed-off-by: Joakim Ahrlin <joakim.ahrlin@gmail.com>

deploy/crds/crd-certificates.yaml

@@ -190,6 +190,9 @@ spec:
                     rotationPolicy:
                       description: RotationPolicy controls how private keys should be regenerated when a re-issuance is being processed. If set to Never, a private key will only be generated if one does not already exist in the target `spec.secretName`. If one does exists but it does not have the correct algorithm or size, a warning will be raised to await user intervention. If set to Always, a private key matching the specified requirements will be generated whenever a re-issuance occurs. Default is 'Never' for backward compatibility.
                       type: string
+                      enum:
+                        - Never
+                        - Always
                     size:
                       description: Size is the key bit size of the corresponding private key for this certificate. If `algorithm` is set to `RSA`, valid values are `2048`, `4096` or `8192`, and will default to `2048` if not specified. If `algorithm` is set to `ECDSA`, valid values are `256`, `384` or `521`, and will default to `256` if not specified. If `algorithm` is set to `Ed25519`, Size is ignored. No other values are allowed.
                       type: integer

pkg/apis/certmanager/v1/types_certificate.go

@@ -212,6 +212,7 @@ type CertificatePrivateKey struct {
 	// will be generated whenever a re-issuance occurs.
 	// Default is 'Never' for backward compatibility.
 	// +optional
+	// +kubebuilder:validation:Enum=Never;Always
 	RotationPolicy PrivateKeyRotationPolicy `json:"rotationPolicy,omitempty"`
 
 	// The private key cryptography standards (PKCS) encoding for this