Make s3 bucket variable work

bonus: instruction not to include s3:// in the bucket name

cookiecutter.json

@@ -3,5 +3,5 @@
     "repo_name": "{{ cookiecutter.project_name|replace(' ', '_') }}",
     "author_name": "Your name (or your organization/company/team)",
     "description": "A short description of the project.",
-    "s3_bucket": "your-bucket-for-syncing-data"
+    "s3_bucket": "your-bucket-for-syncing-data (do not include 's3://')"
 }