Remove instruction to add deb-src... lucid partner

Even though it gets added to /etc/sources.list, newer versions of ubuntu
complain about this line not being valid (noticed in 11.04 and 11.10).
Also, this line is not needed to install sun-java6-jdk.

Change-Id: I8d7236fa354bf1ccfef0ed0d1ee2d5e7a11a3043
diff --git a/src/source/initializing.md b/src/source/initializing.md
index e15df10..0dce435 100644
--- a/src/source/initializing.md
+++ b/src/source/initializing.md
@@ -51,7 +51,6 @@
 Java 6: for Gingerbread and newer
 
     $ sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
-    $ sudo add-apt-repository "deb-src http://archive.canonical.com/ubuntu lucid partner"
     $ sudo apt-get update
     $ sudo apt-get install sun-java6-jdk