Elaborate installation via git (fixes p2#12)

README.md

@@ -11,6 +11,38 @@ Supported OAuth2 [flows](#flows) are the _code grant_ (`response_type=code`) and
 Since the Swift language is constantly evolving I am [adding tags](https://github.com/p2/OAuth2/releases) to mark which revision should work with which Swift version.
 
 
+Installation
+------------
+
+Currently the best way to obtain the framework is via git.
+
+#### git
+
+Using Terminal.app, clone the OAuth2 repository, best into a subdirectory of your app project:  
+
+    $ cd path/to/your/app
+    $ git clone https://github.com/p2/OAuth2.git
+
+If you're using git you'll want to add it as a submodule.
+Once cloning completes, open your app project in Xcode and add `OAuth2.xcodeproj` to your app:
+
+![Adding to Xcode](assets/step-adding.png)
+
+Now link the framework to your app:
+
+![Linking](assets/step-linking.png)
+
+These three steps are needed to:
+
+1. Make your App also build the framework
+2. Link the framework into your app
+3. Embed the framework in your app when distributing
+
+> NOTE that as of Xcode 6.2, the "embed" step happens in the "General" tab.
+> You may want to perform step 2 and 3 from the "General" tab.
+> Also make sure you select the framework for the platform (OS X vs. iOS).
+> This is currently a bit tricky since Xcode shows both as _OAuth2.framework_; I've filed a bug report with Apple so that it also shows the target name, fingers crossed.
+
 Usage
 -----
 
@@ -146,7 +178,7 @@ License
 This code is released under the _Apache 2.0 license_, which means that you can use it in open as well as closed source projects.
 Since there is no `NOTICE` file there is nothing that you have to include in your product.
 
-> Copyright 2014 Pascal Pfiffner
+> Copyright 2015 Pascal Pfiffner
 > 
 > Licensed under the Apache License, Version 2.0 (the "License");
 > you may not use this file except in compliance with the License.