Fix spelling

Summary: s/assiciated/associated

Reviewed By: ericniebler

Differential Revision: D19645433

fbshipit-source-id: 844f3f782a083030dbab5b8196c98fb562f0f7de

folly/Expected.h

@@ -71,14 +71,14 @@ constexpr Expected<typename std::decay<Value>::type, Error> makeExpected(
     Value&&);
 
 /**
- * Alias for an Expected type's assiciated value_type
+ * Alias for an Expected type's associated value_type
  */
 template <class Expected>
 using ExpectedValueType =
     typename std::remove_reference<Expected>::type::value_type;
 
 /**
- * Alias for an Expected type's assiciated error_type
+ * Alias for an Expected type's associated error_type
  */
 template <class Expected>
 using ExpectedErrorType =