Update installation instructions

Author: pointlessone

README.md

@@ -7,8 +7,14 @@ govet examines Go source code and reports suspicious constructs, such as Printf
 ### Installation
 
 1. If you haven't already, [install the Code Climate CLI](https://github.com/codeclimate/codeclimate).
-2. Run `codeclimate engines:enable govet`. This command both installs the engine and enables it in your `.codeclimate.yml` file.
-3. You're ready to analyze! Browse into your project's folder and run `codeclimate analyze`.
+2. Add the following to your Code Climate config:
+  ```yaml
+  plugins:
+    govet:
+      enabled: true
+  ```
+3. Run `codeclimate engines:install`
+4. You're ready to analyze! Browse into your project's folder and run `codeclimate analyze`.
 
 ### Building