Fix link

Author: GuillaumeGomez

src/libstd/ffi/os_str.rs

@@ -351,9 +351,6 @@ impl From<String> for OsString {
     /// Converts a [`String`] into a [`OsString`].
     ///
     /// The conversion copies the data, and includes an allocation on the heap.
-    ///
-    /// [`String`]: ../string/struct.String.html
-    /// [`OsString`]: struct.OsString.html
     fn from(s: String) -> OsString {
         OsString { inner: Buf::from_string(s) }
     }