added feedback

Author: ashwinkumar12345

docs/ism/refresh-analyzer.md

@@ -13,3 +13,25 @@ With ISM installed, you can refresh search analyzers in real time with the follo
 POST /_opendistro/_refresh_search_analyzers/<index or alias or wildcard>
 ```
 For example, if you change the synonym list in your analyzer, the change takes effect without you needing to close and reopen the index.
+
+To work, the token filter must have an `updateable` flag of `true`:
+
+```json
+{
+  "analyzer": {
+    "my_synonyms": {
+      "tokenizer": "whitespace",
+      "filter": [
+        "synonym"
+      ]
+    }
+  },
+  "filter": {
+    "synonym": {
+      "type": "synonym_graph",
+      "synonyms_path": "synonyms.txt",
+      "updateable": true
+    }
+  }
+}
+```