Update readme

Author: Raymond McCrae

README.md

@@ -1,2 +1,30 @@
-# swift-jsonpatch
-json-patch [RFC6902] implementation in Swift
+# JSONPatch - Swift 4 json-patch implementation
+JSONPatch is a a swift module implements json-patch [RFC6902](https://tools.ietf.org/html/rfc6902). JSONPatch uses [JSONSerialization](https://developer.apple.com/documentation/foundation/jsonserialization) from Foundation, and has no dependencies on third-party libraries.
+
+The implementation uses the [JSON Patch Tests](https://github.com/json-patch/json-patch-tests) project for unit tests to validate its correctness.
+
+The module currently only supports applying json-patches, and does not support generating a patch based on the differences between two json documents.
+
+# Release
+0.1 - Initial Release
+
+# Usage
+```swift
+import JSONPatch
+
+let jsonstr = """
+              {"foo": "bar"}
+              """
+let patchstr = """
+               {"op": "add", "path": "/baz", "value": "qux"}
+               """
+
+let json = Data(jsonstr.utf8)
+let patch = try! JSONPatch(data: Data(patchstr.utf8))
+let patched = try! patch.apply(to: json)
+```
+
+
+# License
+
+Apache License v2.0