docs needed clarifying on what Packer would do.

Document this feature in ebs-volume.

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

@@ -150,8 +150,15 @@ builder.
     after all provisioners have run. For Windows instances, it is sometimes
     desirable to [run Sysprep](http://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ami-create-standard.html)
     which will stop the instance for you. If this is set to true, Packer *will not*
-    stop the instance and will wait for you to stop it manually. You can do this
-    with a [windows-shell provisioner](https://www.packer.io/docs/provisioners/windows-shell.html).
+    stop the instance but will assume that you will send the stop signal
+    yourself through your final provisioner. You can do this with a
+    [windows-shell provisioner](https://www.packer.io/docs/provisioners/windows-shell.html).
+
+    Note that Packer will still wait for the instance to be stopped, and failing
+    to send the stop signal yourself, when you have set this flag to `true`,
+    will cause a timeout.
+
+    Example of a valid shutdown command:
 
     ``` json
     {

website/source/docs/builders/amazon-ebssurrogate.html.md

@@ -143,8 +143,15 @@ builder.
     after all provisioners have run. For Windows instances, it is sometimes
     desirable to [run Sysprep](http://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ami-create-standard.html)
     which will stop the instance for you. If this is set to true, Packer *will not*
-    stop the instance and will wait for you to stop it manually. You can do this
-    with a [windows-shell provisioner](https://www.packer.io/docs/provisioners/windows-shell.html).
+    stop the instance but will assume that you will send the stop signal
+    yourself through your final provisioner. You can do this with a
+    [windows-shell provisioner](https://www.packer.io/docs/provisioners/windows-shell.html).
+
+    Note that Packer will still wait for the instance to be stopped, and failing
+    to send the stop signal yourself, when you have set this flag to `true`,
+    will cause a timeout.
+
+    Example of a valid shutdown command:
 
     ``` json
     {

website/source/docs/builders/amazon-ebsvolume.html.md

@@ -111,6 +111,27 @@ builder.
     provider whose API is compatible with aws EC2. Specify another endpoint
     like this `https://ec2.custom.endpoint.com`.
 
+-   `disable_stop_instance` (boolean) - Packer normally stops the build instance
+    after all provisioners have run. For Windows instances, it is sometimes
+    desirable to [run Sysprep](http://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ami-create-standard.html)
+    which will stop the instance for you. If this is set to true, Packer *will not*
+    stop the instance but will assume that you will send the stop signal
+    yourself through your final provisioner. You can do this with a
+    [windows-shell provisioner](https://www.packer.io/docs/provisioners/windows-shell.html).
+
+    Note that Packer will still wait for the instance to be stopped, and failing
+    to send the stop signal yourself, when you have set this flag to `true`,
+    will cause a timeout.
+
+    Example of a valid shutdown command:
+
+    ``` json
+    {
+      "type": "windows-shell",
+      "inline": ["\"c:\\Program Files\\Amazon\\Ec2ConfigService\\ec2config.exe\" -sysprep"]
+    }
+    ```
+
 -   `ebs_optimized` (boolean) - Mark instance as [EBS
     Optimized](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSOptimized.html).
     Default `false`.