make dead code required in readme

Author: Poonam-raj

Sprint-3/readme.md

@@ -12,7 +12,7 @@ This sprint you are expected to produce multiple different pull requests:
 
 1. One pull request for the `1-implement-and-rewrite-tests` directory.
 2. One pull request for the `2-practice-tdd` directory.
-3. As a stretch goal, one pull request for the `3-dead-code` directory.
+3. One pull request for the `3-dead-code` directory.
 4. Optionally, one pull request for the `4-stretch` directory.
 
 Each directory contains a README.md file with instructions for that directory.