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

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

Author: lucatorella

Darwin/Foundation-swiftoverlay/NSStringAPI.swift

@@ -1671,7 +1671,7 @@ extension StringProtocol where Index == String.Index {
   /// Returns `true` if `other` is non-empty and contained within `self` by
   /// case-sensitive, non-literal search. Otherwise, returns `false`.
   ///
-  /// 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, *) {