[DOCS] Identify reloadable GCS repository plugin settings (#46352)

docs/plugins/repository-gcs.asciidoc

@@ -158,9 +158,9 @@ bin/elasticsearch-keystore add-file gcs.client.default.credentials_file /path/se
 The following are the available client settings. Those that must be stored in the keystore
 are marked as `Secure`.
 
-`credentials_file`::
+`credentials_file` ({ref}/secure-settings.html[Secure], {ref}/secure-settings.html#reloadable-secure-settings[reloadable])::
 
-    The service account file that is used to authenticate to the Google Cloud Storage service. (Secure)
+    The service account file that is used to authenticate to the Google Cloud Storage service.
 
 `endpoint`::
 

docs/reference/setup/secure-settings.asciidoc

@@ -124,4 +124,5 @@ of reloading after each modification.
 There are reloadable secure settings for:
 
 * {plugins}/discovery-ec2-usage.html#_configuring_ec2_discovery[The EC2 discovery plugin]
+* {plugins}/repository-gcs-client.html[The GCS repository plugin]
 * {plugins}/repository-s3-client.html[The S3 repository plugin]