Update README.md

Author: qqpann

README.md

@@ -54,6 +54,7 @@ The concept is to assume the opponent will take their best move and try to minim
 - MiniMax <https://en.wikipedia.org/wiki/Minimax>
 - Alpha-beta pruning <https://en.wikipedia.org/wiki/Alpha–beta_pruning>
 - Negamax <https://en.wikipedia.org/wiki/Negamax>
+- NegaScout (PVS, principal variation search) <https://en.wikipedia.org/wiki/Principal_variation_search>
 
 ### Value Iteration