Improve Getting Started documentation.

Fix #53

Author: dragos

.gitignore

@@ -11,3 +11,4 @@ out/
 *.log
 scala/server/ensimeServer-assembly*
 coursier
+.hydra

scala/README.md

@@ -12,6 +12,12 @@ If you find this useful, please file tickets and contribute fixes. I'm working o
 
 If you can't contribute your time but would like to donate, please [donate to the Ensime project](http://ensime.org/sponsor/) instead. This plugin delegates to Ensime for most of its features.
 
+# Setting up
+
+This extension is based on [Ensime](http://ensime.org), so you need to create an Ensime configuration file before you can use it. This file lists source directories, classpath entries and compiler arguments. If you have an Sbt project just add the [sbt-ensime](http://ensime.org/build_tools/sbt/) plugin and follow the guide (other build tools are [supported](http://ensime.org/build_tools/)). Then just run `sbt ensimeConfig` and voilà!
+
+(If you already started Code, it should detect that a new `.ensime` file was created and pick up the project).
+
 # Setting the JDK
 
 The path to the Java Development Kit is searched in the following order: