Update README (#2)

Add some contents to README and minor code cleanup

Author: yim-lee

README.md

@@ -1,4 +1,59 @@
-# Asynchronous Resolver
+# Swift Asynchronous DNS Resolver
 
 A Swift library for asynchronous DNS requests, wrapping [c-ares](https://github.com/c-ares/c-ares) with Swift-friendly APIs and data structures.
 
+## Project status
+
+This is the beginning of a community-driven open-source project actively seeking contributions, be it code, documentation, or ideas.
+
+## Getting started
+
+If you have a server-side Swift application or a cross-platform (e.g. Linux, macOS) application that needs DNS resolution, Swift Asynchronous DNS Resolver is a great idea. Below you will find all you need to know to get started.
+
+### Adding the dependency
+
+To add a dependency on the package, declare it in your `Package.swift`:
+
+```swift
+.package(url: "https://github.com/apple/swift-async-dns-resolver.git", from: "0.1.0"),
+```
+
+and to your application target, add `AsyncDNSResolver` to your dependencies:
+
+```swift
+.target(name: "MyApplication", dependencies: ["AsyncDNSResolver"]),
+```
+
+###  Using a DNS resolver
+
+```swift
+// import the package
+import AsyncDNSResolver
+
+// initialize the DNS resolver
+let resolver = AsyncDNSResolver()
+
+// run a query
+self.resolver.query(.A(name: "apple.com") { result in
+    switch result {
+    case .success(let aRecords):
+        // process the ARecords
+    case .failure(let error):
+        // process the error
+    }
+})
+```
+
+## Detailed design
+
+The main types in the library are `AsyncDNSResolver`, `AsyncDNSResolver.Query`, and `AsyncDNSResolver.Options`.
+
+`AsyncDNSResolver` uses the C-library [c-ares](https://github.com/c-ares/c-ares) underneath and delegates all queries to it.
+
+`AsyncDNSResolver.Query` defines the supported DNS query types, while `AsyncDNSResolver.Options` provides different options for configuring `AsyncDNSResolver`.
+
+The current implementation relies on a `DispatchQueue` to process queries asynchronously. An implementation that makes use of an event loop might be better. 
+
+---
+
+Do not hesitate to get in touch, over on https://forums.swift.org/c/server.

Tests/AsyncDNSResolverTests/AsyncDNSResolverTests.swift

@@ -23,9 +23,6 @@ final class AsyncDNSResolverTests: XCTestCase {
     override func setUp() {
         super.setUp()
 
-//        var options = AsyncDNSResolver.Options()
-//        options.servers = ["8.8.8.8"]
-//        self.resolver = try! AsyncDNSResolver(options: options)
         self.resolver = try! AsyncDNSResolver()
     }