Add example file so required files section in docs looks correct

Change-Id: Idbba7fe25ef7ebcaa488242cc369aa3f619ff98e

doc/source/index.rst

@@ -20,17 +20,8 @@ Required variables
 To install molteniron nodes, please add the following set of information:
 There can be more than one bare metal node.
 
-  molteniron_baremetal_nodes:
-    - name: test1
-      ipmi_ip: 10.1.2.1
-      ipmi_user: user
-      ipmi_password: password
-      allocation_pool: 10.1.2.3,10.1.2.4
-      port_hwaddr: de:ad:be:ef:00:01
-      cpu_arch: ppc64el
-      cpus: 8
-      ram_mb: 2048
-      disk_gb: 32
+.. literalinclude:: ../../examples/required_variables.yml
+   :language: yaml
 
 Example playbook
 ~~~~~~~~~~~~~~~~

examples/required_variables.yml

@@ -0,0 +1,13 @@
+# To install molteniron nodes, please add the following set of information:
+# There can be more than one bare metal node.
+molteniron_baremetal_nodes:
+  - name: test1
+    ipmi_ip: 10.1.2.1
+    ipmi_user: user
+    ipmi_password: password
+    allocation_pool: 10.1.2.3,10.1.2.4
+    port_hwaddr: de:ad:be:ef:00:01
+    cpu_arch: ppc64el
+    cpus: 8
+    ram_mb: 2048
+    disk_gb: 32