Merge pull request #24 from ciceropablo/patch-2

Update CONTRIBUTING.md

Author: thinkingserious

CONTRIBUTING.md

@@ -127,7 +127,7 @@ python -m unittest discover -v
 
 All PRs require passing tests before the PR will be reviewed.
 
-### Prequisites: ###
+### Prerequisites: ###
 
 The above local "Initial setup" is complete