Documentation: add JDK configuration note

Point user to call lunch before building. lunch will set
the correct JAVA_HOME to Sun JDK.

Tested on Ubuntu 11.10 32-bit

Change-Id: Idec2fbaa0190c145ec06f41a101b56b91cc09531
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
diff --git a/src/source/initializing.md b/src/source/initializing.md
index 7d90f43..51f5123 100644
--- a/src/source/initializing.md
+++ b/src/source/initializing.md
@@ -67,6 +67,9 @@
     $ sudo apt-get update
     $ sudo apt-get install sun-java5-jdk
 
+*Note: The `lunch` command in the build step will ensure that the Sun JDK is
+used instead of any previously installed JDK.*
+
 ## Installing required packages (Ubuntu 10.04 -- 11.10) ##
 
 Ubuntu 10.04 64-bit is recommended.  Building using a newer version of Ubuntu or a 32-bit Ubuntu is