update readme

Author: StarLard

README.md

@@ -1,2 +1,20 @@
 # SeaweedKit
-A pure Swift SDK for consuming the official Magicseaweed API
+A pure Swift SDK for consuming the official [Magicseaweed API](https://magicseaweed.com/docs/developers/59/api/9905/)
+
+## Installation
+
+SeaweedKit is available through [Swift Package Manager](https://swift.org/package-manager/), a dependency manager built into Xcode.
+
+If you are using Xcode 11 or higher, go to **File / Swift Packages / Add Package Dependency...** and enter package repository URL **https://github.com/StarLard/SeaweedKit.git**, then follow the instructions.
+
+To remove the dependency, select the project and open **Swift Packages** (which is next to **Build Settings**). You can add and remove packages from this tab.
+
+> Swift Package Manager can also be used [from the command line](https://swift.org/package-manager/).
+
+## Author
+
+[@StarLard](https://twitter.com/CalebFriden)
+
+## License
+
+SeaweedKit is available under the Apache 2.0 license. See the LICENSE file for more info.