Merge pull request #30 from adjust/v3.0.0

Add cocoapods instructions to Readme

Author: wellle

README.md

@@ -13,6 +13,8 @@ If you're using [CocoaPods][cocoapods], you can add the following line to your
 `Podfile` and continue with [step 3](#step3):
 
 ```ruby
+pod 'Adjust', :git => 'git://github.com/adeven/adjust_ios_sdk.git', :tag => 'v3.0.0'
+```
 
 ### 1. Get the SDK