Update installation instructions

Manual.org

@@ -132,6 +132,7 @@ To use this playbook on a Ubuntu Server Installation you need to run the followi
 sudo apt-get install git
 git clone https://github.com/yavdr/yavdr-ansible.git
 cd yavdr-ansible
+git checkout bionic
 sudo ./install-yavdr.sh
 #+END_SRC
 
@@ -1682,7 +1683,6 @@ b'\xde\xad\xbe\xef'
 *** default variables
 #+BEGIN_SRC yaml :tangle roles/yavdr-xorg/defaults/main.yml :mkdirp yes :padline no
 first_run: False
-xorg_data: {}
 #+END_SRC
 *** tasks