Adding Levenshtein distance to the README

Author: rlishtaba

README.md

@@ -615,7 +615,8 @@ thereby saving computation time at the expense of a (hopefully) modest expenditu
 so as to facilitate its lookup.) The technique of storing solutions to subproblems instead of recomputing them is called "memoization".
 
 
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+### Levenshtein distance
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 In information theory, Linguistics and computer science, the Levenshtein distance is a string metric for measuring the difference between two sequences.
 Informally, the Levenshtein distance between two words is the minimum number of single-character edits (insertions, deletions or substitutions) required to change one word into the other.
 It is named after Vladimir Levenshtein, who considered this distance in 1965.