Update README.md

Author: seanchen1991

README.md

@@ -20,7 +20,7 @@ Commit your code regularly and meaningfully. This helps both you (in case you ev
 
 This Sprint Challenge is split into three parts:
 
-1. Writing an algorithm to traverse through a binary search tree
+1. Implement a data structure called a ring buffer (description in the README in the `ring_buffer` directory
 2. Optimizing some inefficient code
 3. Analyzing time and space complexities from parts 1 and 2