Update installation.md
Change default environment from Ubuntu 16.04 to 18.04
@@ -35,7 +35,7 @@ $ cd claw-playbook
$ vagrant up
```
-By default, this provisions an Ubuntu 16.04 environment. If you would prefer to use CENTOS 7 instead, set the `ISLANDORA_DISTRO`
+By default, this provisions an Ubuntu 18.04 environment. If you would prefer to use CENTOS 7 instead, set the `ISLANDORA_DISTRO`
environment variable to `centos/7`. To prevent having to do this every time you open a new shell, add the following command to
your `.bashrc` file
