Update sbt build command to create JARs

README.md

@@ -17,7 +17,7 @@ Spark requires Scala 2.9.1. This version has been tested with 2.9.1.final.
 The project is built using Simple Build Tool (SBT), which is packaged with it.
 To build Spark and its example programs, run:
 
-    sbt/sbt compile
+    sbt/sbt package
 
 To run Spark, you will need to have Scala's bin in your `PATH`, or you
 will need to set the `SCALA_HOME` environment variable to point to where