Re-arranging the readme file propsa (#748)

The top of the readme should usually contain information about how to install the tool. I would suggest pushing down the "Run test" to the bottom after the users are able to install the tool and understand how to use it first

Thanks

README.md

@@ -19,12 +19,6 @@ You can install the latest stable release of node.js from [here](https://nodejs.
 npm install -g oav@latest
 ```
 
-### Run API test
-
-OAV support run API test against Azure and validate request and response. You could define API scenario file which compose with several swagger example files and then use oav to execute it. For more details about API test, please refer to this [API scenario documentation](https://github.com/Azure/azure-rest-api-specs/tree/main/documentation/api-scenario).
-
-![](./documentation/runApiTest.gif)
-
 #### Command usage:
 
 ```bash
@@ -125,6 +119,12 @@ pipeline:
     input: swagger-document/identity
 ```
 
+### Run API test
+
+OAV support run API test against Azure and validate request and response. You could define API scenario file which compose with several swagger example files and then use oav to execute it. For more details about API test, please refer to this [API scenario documentation](https://github.com/Azure/azure-rest-api-specs/tree/main/documentation/api-scenario).
+
+![](./documentation/runApiTest.gif)
+
 ### Live Validation Mode
 
 - A **Live Validation** mode has been added to OAV with the purpose of enabling validation of live traffic.