Declare dynamic refresh support for ExternalStorageReadOnly policy

components/policy/resources/policy_templates.json

Index: components/policy/resources/policy_templates.json
diff --git a/components/policy/resources/policy_templates.json b/components/policy/resources/policy_templates.json
index 18682b8561714e206c5e792c5d71435d7c288e86..2f889747a1bb96fa39ffa8386aa7343c6a55c691 100644
--- a/components/policy/resources/policy_templates.json
+++ b/components/policy/resources/policy_templates.json
@@ -5812,9 +5812,17 @@
       'tags': [],
       'supported_on': ['chrome_os:54-'],
       'caption': '''Treat external storage devices as read-only.''',
-      'desc': '''When this policy is set to true, users cannot write anything to external storage devices.''',
+      'desc': '''Treat external storage devices as read-only.
+
+      This policy is effective only when ExternalStorageDisabled is set to false or not configured.
+
+      When this policy is set to true, users cannot write anything to external storage devices.
+
+      If this setting is disabled or not configured then users can create and modify files of external storage devices which are physically writable.
+
+      Dynamic refresh of this policy is supported in M56 and later.''',
       'features': {
-        'dynamic_refresh': False,
+        'dynamic_refresh': True,
         'per_profile': True,
       },
       'example_value': True