docs(README): add installation command for serverless plugin

Author: vavasilva

README.md

@@ -6,6 +6,9 @@ A Serverless Framework plugin that adds request validation to your AWS API Gatew
 
 ```bash
 npm install --save-dev serverless-api-gateway-request-validator
+
+# Using Serverless plugin install
+serverless plugin install -n serverless-api-gateway-request-validator
 ```
 
 Then add the plugin to your `serverless.yml` file:

package.json

@@ -1,6 +1,6 @@
 {
   "name": "serverless-api-gateway-request-validator",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "Serverless Framework plugin to configure API Gateway request validators",
   "main": "src/index.js",
   "scripts": {