Fix the comment for the Job managedBy field

Author: mimowo

api/openapi-spec/swagger.json

@@ -345,7 +345,7 @@
             "type": "integer"
           },
           "managedBy": {
-            "description": "ManagedBy field indicates the controller that manages a Job. The k8s Job controller reconciles jobs which don't have this field at all or the field value is the reserved string `kubernetes.io/job-controller`, but skips reconciling Jobs with a custom value for this field. The value must be a valid domain-prefixed path (e.g. acme.io/foo) - all characters before the first \"/\" must be a valid subdomain as defined by RFC 1123. All characters trailing the first \"/\" must be valid HTTP Path characters as defined by RFC 3986. The value cannot exceed 64 characters.\n\nThis field is alpha-level. The job controller accepts setting the field when the feature gate JobManagedBy is enabled (disabled by default).",
+            "description": "ManagedBy field indicates the controller that manages a Job. The k8s Job controller reconciles jobs which don't have this field at all or the field value is the reserved string `kubernetes.io/job-controller`, but skips reconciling Jobs with a custom value for this field. The value must be a valid domain-prefixed path (e.g. acme.io/foo) - all characters before the first \"/\" must be a valid subdomain as defined by RFC 1123. All characters trailing the first \"/\" must be valid HTTP Path characters as defined by RFC 3986. The value cannot exceed 63 characters. This field is immutable.\n\nThis field is alpha-level. The job controller accepts setting the field when the feature gate JobManagedBy is enabled (disabled by default).",
             "type": "string"
           },
           "manualSelector": {

api/openapi-spec/v3/apis__batch__v1_openapi.json

@@ -476,7 +476,8 @@ type JobSpec struct {
 	// The value must be a valid domain-prefixed path (e.g. acme.io/foo) -
 	// all characters before the first "/" must be a valid subdomain as defined
 	// by RFC 1123. All characters trailing the first "/" must be valid HTTP Path
-	// characters as defined by RFC 3986. The value cannot exceed 64 characters.
+	// characters as defined by RFC 3986. The value cannot exceed 63 characters.
+	// This field is immutable.
 	//
 	// This field is alpha-level. The job controller accepts setting the field
 	// when the feature gate JobManagedBy is enabled (disabled by default).

pkg/apis/batch/types.go

@@ -477,7 +477,8 @@ type JobSpec struct {
 	// The value must be a valid domain-prefixed path (e.g. acme.io/foo) -
 	// all characters before the first "/" must be a valid subdomain as defined
 	// by RFC 1123. All characters trailing the first "/" must be valid HTTP Path
-	// characters as defined by RFC 3986. The value cannot exceed 64 characters.
+	// characters as defined by RFC 3986. The value cannot exceed 63 characters.
+	// This field is immutable.
 	//
 	// This field is alpha-level. The job controller accepts setting the field
 	// when the feature gate JobManagedBy is enabled (disabled by default).