Add README

Author: kean

README.md

@@ -1,3 +1,123 @@
 # URLQueryEncoder
 
-A description of this package.
+A customizable Swift `Encoder` that encodes instances of data types as URL query items. Supports all [OpenAPI] query parameter [serialization options](https://swagger.io/docs/specification/serialization/).
+
+## Examples
+
+### Encoding Primitives
+
+```swift
+let encoder = URLQueryEncoder()
+encoder.encode(["id": id])
+
+print(encoder.queryItems)
+// ("id", "5")
+```
+
+### Encoding Arrays
+
+```swift
+let ids = [3, 4, 5]
+let encoder = URLQueryEncoder()
+encoder.encode(["id": ids])
+
+// Query: "id=3&id=4&id=5"
+```
+
+With an `explode` option disabled:
+
+```swift
+let ids = [3, 4, 5]
+let encoder = URLQueryEncoder()
+encoder.encode(["id": ids], explode: false)
+
+// Query: "id=3,4,5"
+```
+
+With an `explode` option disabled and a custom delimiter:
+
+```swift
+let ids = [3, 4, 5]
+let encoder = URLQueryEncoder()
+encoder.encode(["id": ids], explode: false, delimiter: "|")
+
+// Query: "id=3|4|5"
+```
+
+### Encoding Objects
+
+```swift
+let user = User(role: "admin", name: "kean")
+
+let encoder = URLQueryEncoder()
+encoder.encode(user)
+
+// Query: "role=admin&name=kean"
+```
+
+With an `explode` option disabled:
+
+```swift
+let user = User(role: "admin", name: "kean")
+
+let encoder = URLQueryEncoder()
+encoder.encode(user, explode: false)
+
+// Query: "id=role,admin,name,kean"
+```
+
+As a "deep" object:
+
+```swift
+let user = User(role: "admin", name: "kean")
+
+let encoder = URLQueryEncoder()
+encoder.encode(user, isDeepObject: true)
+
+// Query: "id[role]=admin&id[name]=kean")"
+```
+
+## Encoding Options
+
+There are two ways to change the encoding options: settings them directly on `URLQueryEncoder` instance, or passing options in each individual `encode` call. The reason it's designed this way is that in OpenAPI, each parameter can have different serialization options.
+
+```swift
+let encoder = URLQueryEncoder()
+encoder.explode = false
+encoder.isDeepObject = true
+encoder.delimiter = "|"
+encoder.dateEncodingStrategy = .millisecondsSince1970
+```
+
+You can use `URLQueryEncoder` to encode more that one parameter are a time:
+
+```swift
+let user = User(role: "admin", name: "kean")
+let ids = [3, 4, 5]
+
+let encoder = URLQueryEncoder()
+encoder.encode(["ids": ids], explode: false)
+encoder.encode(["ids2": ids], explode: true)
+encoder.encode(["user": user], isDeepObject: true)
+encoder.encode(["id": 2])
+
+// Query: "ids=3,4,5&ids2=3&ids2=4&ids2=5&user[role]=admin&user[name]=kean&id=2")
+```
+
+## Accessing Results
+
+You can access the encoding results at any time, and they come in different forms:
+
+```swift
+public final class Encoder {
+    public var queryItems: [URLQueryItem]
+    public var items: [(String, String?)]
+    
+    public var query: String?
+    public var percentEncodedQuery: String?
+}
+```
+
+## License
+
+URLQueryEncoder is available under the MIT license. See the LICENSE file for more info.