docs(troubleshooting): added instructions on manually updating CoreOS

Author: adamkdean

docs/troubleshooting_deis/index.rst

@@ -130,6 +130,27 @@ Try destroying the cluster and relaunching the cluster with a fresh discovery UR
 
 You can use ``make discovery-url`` to automatically fetch a new discovery URL.
 
+Manually updating CoreOS
+------------------------
+
+Sometimes you may need to update CoreOS manually in order to get Deis to work. You can do this by ssh'ing onto your servers and running the following commands:
+
+    sudo /usr/bin/systemctl unmask update-engine.service
+    sudo /usr/bin/systemctl start update-engine.service
+    sudo update_engine_client -update
+    sudo /usr/bin/systemctl stop update-engine.service
+    sudo /usr/bin/systemctl mask update-engine.service
+    sudo reboot
+
+You can check the CoreOS version by running the following command on the CoreOS machine:
+    
+    cat /etc/os-release
+    
+Or from your local machine:
+
+    ssh core@<server ip> 'cat /etc/os-release'
+    
+    
 Other issues
 ------------