website/docs: document the rsync synced folder type

website/docs/source/layouts/layout.erb

@@ -173,6 +173,7 @@
 								<ul class="sub unstyled">
 									<li<%= sidebar_current("syncedfolder-basic") %>><a href="/v2/synced-folders/basic_usage.html">Basic Usage</a></li>
 									<li<%= sidebar_current("syncedfolder-nfs") %>><a href="/v2/synced-folders/nfs.html">NFS</a></li>
+									<li<%= sidebar_current("syncedfolder-rsync") %>><a href="/v2/synced-folders/rsync.html">RSync</a></li>
 									<li<%= sidebar_current("syncedfolder-virtualbox") %>><a href="/v2/synced-folders/virtualbox.html">VirtualBox</a></li>
 								</ul>
 								<% end %>

website/docs/source/v2/synced-folders/rsync.html.md

@@ -0,0 +1,50 @@
+---
+page_title: "RSync - Synced Folders"
+sidebar_current: "syncedfolder-rsync"
+---
+
+# RSync
+
+**Synced folder type:** `rsync`
+
+Vagrant can use [rsync](http://en.wikipedia.org/wiki/Rsync) as a mechanism
+to sync a folder to the guest machine. This synced folder type is useful
+primarily in situations where other synced folder mechanisms are not available,
+such as when NFS or VirtualBox shared folders aren't available in the guest
+machine.
+
+The rsync synced folder does a one-time one-way sync from the machine running
+to the machine being started by Vagrant.
+
+## Prerequisites
+
+To use the rsync synced folder type, the machine running Vagrant must have
+`rsync` (or `rsync.exe`) on the path. This executable is expected to behave
+like the standard rsync tool.
+
+## Options
+
+The rsync synced folder type accepts the following options:
+
+* `rsync__exclude` (string or array of strings) - A list of files or directories
+  to exclude from the sync. The values can be any acceptable rsync exclude
+  pattern. By default, the ".vagrant/" directory is excluded. We recommend
+  excluding revision control directories such as ".git/" as well.
+
+## Example
+
+The following is an example of using RSync to sync a folder:
+
+<pre class="prettyprint">
+Vagrant.configure("2") do |config|
+  config.vm.synced_folder ".", "/vagrant", type: "rsync",
+    rsync__exclude: ".git/"
+end
+</pre>
+
+## Re-Syncing
+
+The rsync sync is done only during a `vagrant up` or `vagrant reload`. It
+is not currently possible to force a re-sync in any way other than reloading.
+
+We plan on exposing a command to force a sync in a future version of Vagrant.