Fix reference to range(of:) in the contains doc

Signed-off-by: Luca Torella <[email protected]>

Author: lucatorella

Foundation/NSStringAPI.swift

@@ -1633,7 +1633,7 @@ extension StringProtocol where Index == String.Index {
   /// Returns `true` iff `other` is non-empty and contained within
   /// `self` by case-sensitive, non-literal search.
   ///
-  /// Equivalent to `self.rangeOfString(other) != nil`
+  /// Equivalent to `self.range(of: other) != nil`
   public func contains<T : StringProtocol>(_ other: T) -> Bool {
     let r = self.range(of: other) != nil
     if #available(macOS 10.10, iOS 8.0, *) {