docs: Add JSON client usage instructions to the README

README.md

@@ -38,3 +38,16 @@ To disconnect from the broker:
 ```
 
 For more detailed usage, see the API documentation and the example code in the `examples` directory.
+
+## JSON Client
+
+Milquetoast also provides a JSON client, which automatically parses JSON payloads from received messages and serializes JSON payloads for sent messages. 
+
+To connect using the JSON client:
+
+```clojure
+(def json-client (milquetoast.api/connect-json! :host "localhost" :port 1883))
+```
+
+The JSON client can be used in the same way as the regular client, but note that the payload of received messages will be a map (parsed from the JSON payload), and the payload of sent messages should be a map (which will be serialized to a JSON string).
+```