Tweak grammar

Author: joshtriplett

library/std/src/io/error.rs

@@ -496,7 +496,7 @@ impl Error {
     /// // errors can also be created from other errors
     /// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
     ///
-    /// // creating an error without payload (also without memory allocation)
+    /// // creating an error without payload (and without memory allocation)
     /// let eof_error = Error::from(ErrorKind::UnexpectedEof);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]