Replace all ~"" with "".to_owned()

src/libstd/io/mod.rs

@@ -1188,7 +1188,7 @@ pub trait Buffer: Reader {
     /// use std::io;
     ///
     /// let mut reader = io::stdin();
-    /// let input = reader.read_line().ok().unwrap_or(~"nothing");
+    /// let input = reader.read_line().ok().unwrap_or("nothing".to_owned());
     /// ```
     ///
     /// # Error