Adding more detail on how flattened values work when multiValued = true.

daprdocs/content/en/reference/components-reference/supported-secret-stores/file-secret-store.md

@@ -45,7 +45,7 @@ spec:
 
 ## Setup JSON file to hold the secrets
 
-Given the following json:
+Given the following JSON loaded from `secretsFile`:
 
 ```json
 {
@@ -82,6 +82,31 @@ If `multiValued` is `"true"`, you would instead use the top level key. In this e
 }
 ```
 
+Nested structures after the top level will be flattened. In this example, `connectionStrings` would return the following map:
+
+JSON from `secretsFile`:
+
+```json
+{
+    "redisPassword": "your redis password",
+    "connectionStrings": {
+        "mysql": {
+          "username": "your mysql username",
+          "password": "your mysql password"
+        }
+    }
+}
+```
+
+Response:
+
+```json
+{
+  "mysql:username": "your mysql username",
+  "mysql:password": "your mysql password"
+}
+```
+
 This is useful in order to mimic secret stores like Vault or Kubernetes that return multiple key/value pairs per secret key.
 
 ## Related links