Update README

README.md

@@ -1,3 +1,45 @@
 # Base16
 
 An extension of Swift's `Data` type to work with hexadecimal (Base16) encoding.
+
+- [Installation](#installation)
+- [Usage](#usage)
+- [License](#license)
+
+## Installation
+
+### Swift Package Manager
+
+Add a dependency to `https://github.com/metabolist/base16.git`, either in Xcode or by adding it to the `dependencies` array in your `Package.swift`:
+
+```swift
+dependencies: [
+    .package(name: "Base16", url: "https://github.com/metabolist/base16.git", .upToNextMajor(from: "1.0.0"))
+],
+```
+
+## Usage
+
+Base16 adds functions to `Data` that mirror `Foundation`'s functions for working with Base64 encoded data:
+
+```swift
+let data = Data([182, 239, 215, 173, 251, 168, 76, 252,
+                 140, 7, 39, 163, 56, 255, 171, 35,
+                 121, 205, 26, 252, 53, 166, 159, 67,
+                 100, 70, 140, 79, 47, 26, 138, 209])
+
+data.base16EncodedString() // returns "b6efd7adfba84cfc8c0727a338ffab2379cd1afc35a69f4364468c4f2f1a8ad1"
+data.base16EncodedString(options: [.uppercase]) // returns "B6EFD7ADFBA84CFC8C0727A338FFAB2379CD1AFC35A69F4364468C4F2F1A8AD1"
+data.base16EncodedData() // returns the same thing as `base16EncodedString()` as UTF-8 data
+data.base16EncodedData(options: [.uppercase]) // returns the same thing as `base16EncodedString(options: [.uppercase])` as UTF-8 data
+
+try Data(base16Encoded: "b6efd7adfba84cfc8c0727a338ffab2379cd1afc35a69f4364468c4f2f1a8ad1") // equivalent to `data` variable above
+try Data(base16Encoded: "B6EFD7ADFBA84CFC8C0727A338FFAB2379CD1AFC35A69F4364468C4F2F1A8AD1") // equivalent to `data` variable above
+// The above initializers also exist for Base16 encoded UTF-8 `Data`
+```
+
+A common use case for encoding data to a Base16 string is for representing the `deviceToken` received in `UIApplicationDelegate`'s `application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data)` for registering apps for push notifications.
+
+## License
+
+Base16 is released under the MIT license. [See LICENSE](https://github.com/metabolist/base16/blob/main/LICENSE) for details.