Update README for Carthage (#4)

* Update README

* Better format

README.md

@@ -1,7 +1,7 @@
 ![MirrorDiffKit](https://raw.githubusercontent.com/Kuniwak/MirrorDiffKit/master/Documentation/Images/logo.png)
 =============
 
-![SPM compatible](https://img.shields.io/badge/SPM-compatible-green.svg)
+![SPM compatible](https://img.shields.io/badge/SPM%20%7C%20Carthage-compatible-green.svg)
 [![v0.0.0](https://img.shields.io/badge/version-0.0.0-blue.svg)](https://github.com/Kuniwak/MirrorDiffKit/releases)
 [![MIT license](https://img.shields.io/badge/lisence-MIT-yellow.svg)](https://github.com/Kuniwak/MirrorDiffKit/blob/master/LICENSE)
 [![CircleCI](https://circleci.com/gh/Kuniwak/MirrorDiffKit/tree/master.svg?style=shield)](https://circleci.com/gh/Kuniwak/MirrorDiffKit/tree/master)
@@ -73,9 +73,19 @@ Installation
 ------------
 ### Swift Package Manager
 
-Add the the following line to your `Package.swift`:
+Add the following line to your `Package.swift`:
 
 
 ```
 .Package(url: "https://github.com/Kuniwak/MirrorDiffKit.git")
 ```
+
+
+
+### Carthage
+
+Add the following line to your `Cartfile`:
+
+```
+github "Kuniwak/MirrorDiffKit"
+```