docs(README): add example of usage section

Author: wallace-sf

README.md

@@ -8,6 +8,7 @@ React MQTT Workflow Manager is a React component library designed to wrap all [M
  - [Installation](#installation)
  - [Dependencies](#dependencies)
  - [Usage](#usage)
+ - [Example of usage](#example-of-usage)
  - [Properties](#properties)
  - [WorkflowManagerConfig](#workflowmanagerconfig)
  - [Hooks](#hooks)
@@ -102,6 +103,10 @@ export const store = configureStore({
 
 ```
 
+## [Example of usage](example-of-usage)
+
+See a complete example of usage [here](https://github.com/flow-build/react-mqtt-workflow-manager/tree/master/app/).
+
 ## [Properties](properties)
 
 Property          | Type             | Required             | Description