chore(s3-deployment): Exclude pattern in README example for prune was…

… wrong (aws#9352)

The documentation at https://docs.aws.amazon.com/cdk/api/latest/docs/aws-s3-deployment-readme.html#prune currently mentions that you can create two deployments with different cache policies by using the `exclude` option in the `asset` function. The last deployment aims to only set the cache policy on `index.html` but ends up setting the policy on everything.

According to aws#9146 (comment), an exclude pattern should be preceded by a `'*'` glob pattern, for it to take the desired effect that is mentioned in the documentation (to only include the `index.html` file).

This PR adds the missing `'*'` glob pattern to the documentations example.


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-s3-deployment/README.md

@@ -91,7 +91,7 @@ new BucketDeployment(this, 'BucketDeployment', {
 });
 
 new BucketDeployment(this, 'HTMLBucketDeployment', {
-  sources: [Source.asset('./website', { exclude: ['!index.html'] })],
+  sources: [Source.asset('./website', { exclude: ['*', '!index.html'] })],
   destinationBucket: bucket,
   cacheControl: [CacheControl.fromString('max-age=0,no-cache,no-store,must-revalidate')],
   prune: false,