Note for executing the first build on Windows

The first packer build command includes passing AWS access key and secret key as variables. On Windows, the single quotes must be replaced with double quotes or an AWS error occurs. This may not be obvious to everyone, hence a note. The AWS error (as below) is not adequately self-explanatory. 

Build 'amazon-ebs' errored: Error querying AMI: NoCredentialProviders: no valid providers in chain. Deprecated.
        For verbose messaging see aws.Config.CredentialsChainVerboseErrors

website/source/intro/getting-started/build-image.html.md

@@ -113,6 +113,10 @@ With a properly validated template. It is time to build your first image. This
 is done by calling `packer build` with the template file. The output should look
 similar to below. Note that this process typically takes a few minutes.
 
+-> **Note:** When using packer on Windows, replace the single-quotes in the 
+command below with double-quotes.
+
+
 ``` {.text}
 $ packer build \
     -var 'aws_access_key=YOUR ACCESS KEY' \