docs: clarified wording around the NodePoolUpdateStrategy default behavior

docs: add references for available node image types

PiperOrigin-RevId: 505186848

Author: Google APIs

google/container/v1beta1/cluster_service.proto

@@ -676,7 +676,9 @@ message NodeConfig {
   map<string, string> metadata = 4;
 
   // The image type to use for this node. Note that for a given image type,
-  // the latest version of it will be used.
+  // the latest version of it will be used. Please see
+  // https://cloud.google.com/kubernetes-engine/docs/concepts/node-images for
+  // available image types.
   string image_type = 5;
 
   // The map of Kubernetes labels (key/value pairs) to be applied to each node.
@@ -2558,7 +2560,9 @@ message UpdateNodePoolRequest {
   // - "-": picks the Kubernetes master version
   string node_version = 5 [(google.api.field_behavior) = REQUIRED];
 
-  // Required. The desired image type for the node pool.
+  // Required. The desired image type for the node pool. Please see
+  // https://cloud.google.com/kubernetes-engine/docs/concepts/node-images for
+  // available image types.
   string image_type = 6 [(google.api.field_behavior) = REQUIRED];
 
   // The desired list of Google Compute Engine
@@ -3876,7 +3880,9 @@ message AutoprovisioningNodePoolDefaults {
   // https://cloud.google.com/compute/docs/disks/customer-managed-encryption
   string boot_disk_kms_key = 9;
 
-  // The image type to use for NAP created node.
+  // The image type to use for NAP created node. Please see
+  // https://cloud.google.com/kubernetes-engine/docs/concepts/node-images for
+  // available image types.
   string image_type = 10;
 }
 
@@ -4987,7 +4993,8 @@ message IdentityServiceConfig {
 
 // Strategy used for node pool update.
 enum NodePoolUpdateStrategy {
-  // Default value.
+  // Default value if unset. GKE internally defaults the update strategy to
+  // SURGE for unspecified strategies.
   NODE_POOL_UPDATE_STRATEGY_UNSPECIFIED = 0;
 
   // blue-green upgrade.