add build instructions

Author: jey

README.md

@@ -1,5 +1,16 @@
 # Spock
 
-An interface to [Apache Spark](https://spark.apache.org) for the [Julia](http://www.julia-lang.org) lanaguage.
+An interface to [Apache Spark](https://spark.apache.org) for the [Julia](http://www.julia-lang.org) language.
+
+## Build Instructions
+
+1. Create a symlink from your `spark-assembly` jar to `lib/spark.jar` (or copy it).
+
+  ```
+  mkdir lib
+  ln -s ~/Downloads/spark-1.3.0-bin-hadoop2.4/lib/spark-assembly-1.3.0-hadoop2.4.0.jar lib/spark.jar
+  ```
+
+2. Type `make` to build `spock.jar` and run the tests.
 
 [![Build Status](https://travis-ci.org/jey/Spock.jl.svg?branch=master)](https://travis-ci.org/jey/Spock.jl)