Fix wording for Nash equilibrium description

Author: rahulsavani

doc/tools.enumpoly.rst

@@ -29,7 +29,7 @@ probabilities over a subset of terminal nodes.  The indifference conditions
 used are those for the sequence form defined on the projection of the game
 to that support of actions.  A solution to these equations implies a probability
 distribution over terminal nodes.  The algorithm then searches for
-a profile which is a Nash equilibrium which implements that probability
+a profile that is a Nash equilibrium that implements that probability
 distribution.  If there exists such a profile, a sample one is returned.
 Note that for probability distributions which assign zero probability to some terminal
 nodes, it is generally the case that there are (infinitely) many such profiles.