add troubleshooting to content file

Author: hectorsector

responses/06.1_e-no-response.md

@@ -1,4 +1,7 @@
-You didn't include a response. Try again.
+You didn't include a response. Make sure that:
+- a file called `responses/wecome-text.md` exists
+- the file is in the `add-metadata` branch
+- the file has content (it cannot be empty)
 
 <hr>
 <h3 align="center">When I detect your new commit, I'll respond in this pull request.</h3>