website: fixup some underscores to not be emphasis in the AWS docs

website/source/docs/builders/amazon-ebs.html.markdown

@@ -60,9 +60,9 @@ Optional:
 
 * `ami_block_device_mappings` (array of block device mappings) - Add the block
   device mappings to the AMI. The block device mappings allow for keys:
-  "device_name" (string), "virtual_name" (string), "snapshot_id" (string),
-  "volume_type" (string), "volume_size" (int), "delete_on_termination" (bool),
-  and "iops" (int).
+  "device\_name" (string), "virtual\_name" (string), "snapshot\_id" (string),
+  "volume\_type" (string), "volume\_size" (int), "delete\_on\_termination"
+  (bool), and "iops" (int).
 
 * `ami_description` (string) - The description to set for the resulting
   AMI(s). By default this description is empty.

website/source/docs/builders/amazon-instance.html.markdown

@@ -75,10 +75,10 @@ Optional:
 
 * `ami_block_device_mappings` (array of block device mappings) - Add the block
   device mappings to the AMI. The block device mappings allow for keys:
-  "device_name" (string), "virtual_name" (string), "snapshot_id" (string),
-  "volume_type" (string), "volume_size" (int), "delete_on_termination" (bool),
-  and "iops" (int). See [amazon-ebs](/docs/builders/amazon-ebs.html) for an
-  example template.
+  "device\_name" (string), "virtual\_name" (string), "snapshot\_id" (string),
+  "volume\_type" (string), "volume\_size" (int), "delete\_on\_termination"
+  (bool), and "iops" (int). See [amazon-ebs](/docs/builders/amazon-ebs.html)
+  for an example template.
 
 * `ami_description` (string) - The description to set for the resulting
   AMI(s). By default this description is empty.