Fix a typo in the documentation for "Using Predicates as Matchers".

PiperOrigin-RevId: 496679950
Change-Id: I2842050902876231d49a142165bcbb88d737505d

docs/gmock_cook_book.md

@@ -1158,7 +1158,7 @@ int IsEven(int n) { return (n % 2) == 0 ? 1 : 0; }
 ```
 
 Note that the predicate function / functor doesn't have to return `bool`. It
-works as long as the return value can be used as the condition in in statement
+works as long as the return value can be used as the condition in the statement
 `if (condition) ...`.
 
 ### Matching Arguments that Are Not Copyable