docs: clarified the deprecation of TEMPLATE in intent training phrase type (#938)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 437265289

Source-Link: googleapis/googleapis@8e6b72f

Source-Link: googleapis/googleapis-gen@318cde2
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiMzE4Y2RlMmVlM2JmZDViNDRhY2RmMWY2ZTI1YjhlMGE2NjZmMDc2NCJ9

Author: gcf-owl-bot[bot]

packages/google-cloud-dialogflow/protos/google/cloud/dialogflow/v2beta1/intent.proto

@@ -227,10 +227,10 @@ message Intent {
 
       // Templates are not annotated with entity types, but they can contain
       // @-prefixed entity type names as substrings.
-      // Template mode has been deprecated. Example mode is the only supported
-      // way to create new training phrases. If you have existing training
-      // phrases that you've created in template mode, those will continue to
-      // work.
+      // Note: Template mode has been deprecated. Example mode is the only
+      // supported way to create new training phrases. If you have existing
+      // training phrases in template mode, they will be removed during training
+      // and it can cause a drop in agent performance.
       TEMPLATE = 2 [deprecated = true];
     }