changed to 12.04 and add kernel

Upstream-commit: a118ad90edbb232806345c4038f3e9e68098648c
Component: engine

components/engine/docs/sources/contributing/devenvironment.rst

@@ -5,7 +5,28 @@
 Setting Up a Dev Environment
 ============================
 
-Instructions that have been verified to work on Ubuntu 12.10,
+Instructions that have been verified to work on Ubuntu Precise 12.04 (LTS) (64-bit),
+
+
+Dependencies
+------------
+
+**Linux kernel 3.8**
+
+Due to a bug in LXC docker works best on the 3.8 kernel. Precise comes with a 3.2 kernel, so we need to upgrade it. The kernel we install comes with AUFS built in.
+
+
+.. code-block:: bash
+
+   # install the backported kernel
+   sudo apt-get update && sudo apt-get install linux-image-generic-lts-raring
+
+   # reboot
+   sudo reboot
+
+
+Installation
+------------
 
 .. code-block:: bash