website: update shell provisioner docs

website/source/docs/provisioners/shell.html.markdown

@@ -26,6 +26,8 @@ The example below is fully functional.
 The reference of available configuratin options is listed below. The only
 required element is either "inline" or "path". Every other option is optional.
 
+Exactly _one_ of the following is required:
+
 * `inline` (array of strings) - This is an array of commands to execute.
   The commands are concatenated by newlines and turned into a single file,
   so they are all executed within the same context. This allows you to
@@ -37,12 +39,19 @@ required element is either "inline" or "path". Every other option is optional.
   This path can be absolute or relative. If it is relative, it is relative
   to the working directory when Packer is executed.
 
-* `remote_path` (string) - The path where the script will be uploaded to
-  in the machine. This defaults to "/tmp/script.sh". This value must be
-  a writable location and any parent directories must already exist.
+* `scripts` (array of strings) - An array of scripts to execute. The scripts
+  will be uploaded and executed in the order specified. Each script is executed
+  in isolation, so state such as variables from one script won't carry on to
+  the next.
+
+Optional parameters:
 
 * `execute_command` (string) - The command to use to execute the script.
   By default this is `sh {{ .Path }}`. The value of this is treated as a
   [configuration template](/docs/templates/configuration-templates.html).
   The only available variable in it is `Path` which is the path to the
   script to run.
+
+* `remote_path` (string) - The path where the script will be uploaded to
+  in the machine. This defaults to "/tmp/script.sh". This value must be
+  a writable location and any parent directories must already exist.