Add information on using the build system to the README.

README.md

@@ -1,6 +1,6 @@
 # Realm Object Store
 
-Cross-platform code used accross bindings. Binding developers can choose to use some or all the included functionality
+Cross-platform code used accross bindings. Binding developers can choose to use some or all the included functionality:
 - `object_store`/`schema`/`object_schema`/`property` - contains the structures and logic used to setup and modify realm files and their schema.
 - `shared_realm` - wraps the object_store apis to provide transactions, notifications, realm caching, migrations, and other higher level functionality.
 - `object_accessor`/`results`/`list` - accessor classes, object creation/update pipeline, and helpers for creating platform specific property getters and setters.
@@ -8,8 +8,28 @@ Cross-platform code used accross bindings. Binding developers can choose to use
 
 ## Building
 
-TBD
+The object store's build system currently only suports building for OS X. The object store itself can build for all Apple
+platforms when integrated into a binding.
+
+1. Install CMake. You can download an installer for OS X from the [CMake download page], or install via [Homebrew](http://brew.sh):
+    ```
+    brew install cmake
+    ```
+
+2. Generate build files:
+
+    ```
+    cmake .
+    ```
+
+3. Build:
+
+    ```
+    make
+    ```
 
 ## Testing
 
-TBD
+```
+make run-tests
+```