Debian jessie docs (#1806)

* Add Debian Jessie notes

* Add installation notes for Debian Jessie

docs/debian.md

@@ -0,0 +1,38 @@
+Debian Jessie
+===============
+
+Debian Jessie installation Notes:
+
+- Add 
+  
+  ```GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1"```
+  
+  to /etc/default/grub. Then update with
+  
+  ```
+   sudo update-grub
+   sudo update-grub2
+   sudo reboot
+  ```
+  
+- Add the [backports](https://backports.debian.org/Instructions/) which contain Systemd 2.30 and update Systemd.
+  
+  ```apt-get -t jessie-backports install systemd```
+  
+  (Necessary because the default Systemd version (2.15) does not support the "Delegate" directive in service files)
+  
+- Add the Ansible repository and install Ansible to get a proper version
+
+  ```
+  sudo add-apt-repository ppa:ansible/ansible
+  sudo apt-get update
+  sudo apt.get install ansible
+
+  ```
+
+- Install Jinja2 and Python-Netaddr
+
+  ```sudo apt-get install phyton-jinja2=2.8-1~bpo8+1 python-netaddr```
+  
+  
+Now you can continue with [Preparing your deployment](getting-started.md#starting-custom-deployment)