Add SPM to Readme

README.md

@@ -1,4 +1,4 @@
-[![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
+[![Swift Package Manager compatible](https://img.shields.io/badge/Swift%20Package%20Manager-compatible-brightgreen.svg)](https://github.com/apple/swift-package-manager) [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 
 # TextStyle
 Helps you manage text styles in your app.
@@ -45,7 +45,13 @@ In the Interface Builder set `Text Style` to match your style's name.
 To see style changes right in the Interface Builder use `Designable` [UI elements classes](/TextStyleDesignables.swift). (i.e. `UILabelDesignable`). You should and add them to your project manually.
 
 # Installation
-Using [Carthage](https://github.com/Carthage/Carthage#adding-frameworks-to-an-application). Add the following line to your Cartfile:
+
+### [Swift Package Manager](https://developer.apple.com/documentation/xcode/adding_package_dependencies_to_your_app)
+Open your project in Xcode and select File > Swift Packages > Add Package Dependency. There enter `https://github.com/trafi/TextStyle` as the repository URL.
+
+### [Carthage](https://github.com/Carthage/Carthage#adding-frameworks-to-an-application)
+
+Add the following line to your `Cartfile`:
 ```
 github "Trafi/TextStyle"
 ```