Added instructions for fixing SSH key permissions (#492)

The SSH with Ubuntu Bionic seems to be stricter about permissions.

docs/_docs/upgrade.md

@@ -5,7 +5,7 @@ description: >
   How to upgrade your development environment to the latest release.
 numbered_headings: yes
 date: 2018-10-12T13:07:23+01:00
-modified: 2018-10-14T10:07:43+01:00
+modified: 2018-10-16T10:45:23+01:00
 ---
 
 {% include base_path %}
@@ -143,6 +143,30 @@ rm ~/.local/share/keyrings/login.keyring
 rm ~/.local/share/keyrings/user.keystore
 ```
 
+#### SSH key not loading
+
+If your SSH key isn't loading it may be down to the file permissions. If your
+key is readable by other you will get the following error when trying to load
+key:
+
+```
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+Permissions 0644 for '/home/vagrant/.ssh/id_rsa' are too open.
+It is required that your private key files are NOT accessible by others.
+This private key will be ignored.
+```
+
+To fix the file permissions run the following command from the terminal in the
+client VM:
+
+```bash
+chmod 'go-rwx' ~/.ssh/*
+```
+
+After this is complete logout and log back in so your key is loaded.
+
 ## Change your password
 
 Once provisioning is complete you need to change your password. Login using the

docs/_posts/2018-10-15-2.0.0-release.md

@@ -10,7 +10,7 @@ excerpt: >
   Major release with many changes, read for details...
 read_time: no
 date: 2018-10-15T19:18:26+01:00
-modified: 2018-10-15T19:18:26+01:00
+modified: 2018-10-16T10:38:52+01:00
 ---
 
 {% include base_path %}
@@ -295,6 +295,18 @@ over difficult to remember random passwords.
 **Important:** you need to complete this procedure before you stop/reload the
 VM.
 
+## Fix SSH key permissions
+
+The version of SSH that comes with Ubuntu Bionic will not load an SSH key if
+it's readable by other users. Run the following command from the terminal in the
+client VM to fix the file permissions:
+
+```bash
+chmod 'go-rwx' ~/.ssh/*
+```
+
+After this is complete logout and log back in so your key is loaded.
+
 ## Full change list
 
 For a full list of changes view the