Review changes

src/libcore/macros.rs

@@ -256,7 +256,7 @@ macro_rules! debug_assert_ne {
 /// with converting downstream errors.
 ///
 /// Prefer using `?` syntax to `try!`. `?` is built in to the language and is
-/// more succinct than `try!`, it is the standard method for error propogation.
+/// more succinct than `try!`. It is the standard method for error propagation.
 ///
 /// `try!` matches the given `Result`. In case of the `Ok` variant, the
 /// expression has the value of the wrapped value.