Update README.md (word2word.py)

Author: beling

README.md

@@ -4,7 +4,8 @@ The files include python implementation of some algorithms and data structures:
 - *eratosthenes_sieve.py* contains prime number generator which uses [Sieve of Eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes);
 - *list_based_dict.py* implements a dictionary that stores a list of key-value pairs and mimics the interface of the built-in `dict` type,
 - *diff.py* is a file comparison program based on a generalized algorithm finding the [longest common subsequence](https://en.wikipedia.org/wiki/Longest_common_subsequence),
-- *hanoi_tower.py* solves [Tower of Hanoi](https://en.wikipedia.org/wiki/Tower_of_Hanoi) (using a recursive algorithm) and visualizes the solution (using [pyglet](https://pyglet.org/)).
+- *hanoi_tower.py* solves [Tower of Hanoi](https://en.wikipedia.org/wiki/Tower_of_Hanoi) (using a recursive algorithm) and visualizes the solution (using [pyglet](https://pyglet.org/)),
+- *word2word.py* solves [Doublets (A Word Puzzle By Lewis Carroll)](https://lewiscarrollresources.net/doublets/index.html) using [BFS](https://en.wikipedia.org/wiki/Breadth-first_search).
 
 # Bibliography/references
 [1] Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest and Clifford Stein *Introduction to Algorithms*