update limitation in README

Author: atifali

README.md

@@ -18,12 +18,21 @@ The MQTT data source has the following requirements:
 - The plugin currently does not support all of the MQTT CONNECT packet options.
 - The plugin currently does not support TLS.
 - Including multiple topics in a panel is not yet well supported.
-- This plugin automatically supports topics publishing json formatted messages.
-
+- This plugin automatically supports topics publishing very simple JSON formatted messages. Note that only the following structure is supported as of now:
+```
+{
+    'value1': 1.0,
+    'value2': 2,
+    'value3': 3.33,
+    ...
+}
+```
+We do plan to support more complex JSON data structures in the upcoming releases. Contributions are highly encouraged!
+- This plugin currently attaches timestamps to the messages when they are received, so there is no way to have custom timestamp for messages.
 ## Install the plugin
 
 ### Installation Pre-requisites
-Refer to: [Building a Backend Datasource Plugin](https://grafana.com/tutorials/build-a-streaming-data-source-plugin/)
+Refer to: [Building a Streaming Datasource Backend Plugin](https://grafana.com/tutorials/build-a-streaming-data-source-plugin/)
 ### Installation Steps
 
 1. Clone the plugin to your Grafana plugins directory.
@@ -34,6 +43,8 @@ Refer to: [Building a Backend Datasource Plugin](https://grafana.com/tutorials/b
 
 This plugin currently supports MQTT v3.1.x.
 
+__Note: Since this plugin uses the Grafana Live Streaming API, make sure to use Grafana v8.0+__
+
 ### Verify that the plugin is installed
 
 1. In Grafana from the left-hand menu, navigate to **Configuration** > **Data sources**.