add host_key and bastion_host_key to the docs

website/docs/provisioners/connection.html.markdown

@@ -83,6 +83,9 @@ provisioner "file" {
 
 * `agent_identity` - The preferred identity from the ssh agent for authentication.
 
+* `host_key` - The public key from the remote host or the signing CA, used to
+  verify the connection.
+
 **Additional arguments only supported by the `winrm` connection type:**
 
 * `https` - Set to `true` to connect using HTTPS instead of HTTP.
@@ -100,6 +103,9 @@ The `ssh` connection also supports the following fields to facilitate connnectio
 * `bastion_host` - Setting this enables the bastion Host connection. This host
   will be connected to first, and then the `host` connection will be made from there.
 
+* `bastion_host_key` - The public key from the remote host or the signing CA,
+  used to verify the host connection.
+
 * `bastion_port` - The port to use connect to the bastion host. Defaults to the
   value of the `port` field.