put shell code in fences

Author: jordanstephens

samples/python-s3/README.md

@@ -14,8 +14,10 @@ and then enter the value when prompted.
 
 ## Testing
 
+```bash
 curl -X POST -H 'Content-Type: application/json' -d '{ "first_name" : "jane", "last_name" : "doe" }' https://xxxxxx/upload
 curl https://xxxxxx/download
+```
 
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