Issue geerlingguy#649: Add docs on how to use vagrant-lxc [ci skip]

docs/other/vagrant-lxc.md

@@ -0,0 +1,41 @@
+[`vagrant-lxc` is a Vagrant plugin](https://github.com/fgrehm/vagrant-lxc) that provisions Linux Containers (LXC) rather than VM's such as VirtualBox or VMWare. Although LXC has much better performance, it only works on Linux hosts, and it isn't as well supported or tested by Drupal VM.
+
+### Install dependencies
+
+    sudo apt-get install lxc bridge-utils
+    vagrant plugin install vagrant-lxc
+
+### Load required kernel modules
+
+As containers can't load modules, but inherit them from the host, you need to load these on your host machine.
+
+    sudo modprobe iptable_filter
+    sudo modprobe ip6table_filter
+
+To load these automatically when you boot up your system, you should check the guidelines of your specific distribution. Usually you add them to `/etc/modules` or `/etc/modules-load.d/*`
+
+### Create a [`Vagrantfile.local`](overriding-configurations.md#extending-the-vagrantfile-with-vagrantfilelocal)
+
+    config.vm.networks[0][1][:lxc__bridge_name] = 'vlxcbr1'
+    config.vm.provider :lxc do |lxc|
+      lxc.customize 'cgroup.memory.limit_in_bytes', "#{vconfig['vagrant_memory']}M"
+    end
+
+Read more about how to configure the container in [`vagrant-lxc`'s README.md](https://github.com/fgrehm/vagrant-lxc#readme).
+
+### Modify your `config.yml`
+
+The following boxes have been tested only minimally, choose which one you want.
+
+    # Centos 7
+    vagrant_box: frensjan/centos-7-64-lxc
+
+    # Ubuntu 16.04
+    vagrant_box: nhinds/xenial64
+
+    # Do not interact with the UFW service on Ubuntu.
+    drupalvm_disable_ufw_firewall: false
+
+### Provision the Container
+
+    vagrant up --provider=lxc

mkdocs.yml

@@ -64,6 +64,7 @@ pages:
   - Other Information:
     - 'Networking Notes': 'other/networking.md'
     - 'Vagrant and VirtualBox': 'other/vagrant-virtualbox.md'
+    - 'Vagrant LXC provider': 'other/vagrant-lxc.md'
     - 'Improving Performance': 'other/performance.md'
     - 'BigPipe with Drupal VM': 'other/bigpipe.md'
     - 'Drupal multisite': 'deployment/multisite.md'