Fix links.

Author: ehuss

src/expressions/await-expr.md

@@ -23,12 +23,12 @@ More specifically, an `<expr>.await` expression has the following effect.
    value contained in the [`Poll::Ready`] variant is used as the result
    of the `await` expression itself.
 
-[future]: https://doc.rust-lang.org/std/future/trait.Future.html
+[future]: ../../std/future/trait.Future.html
 [_Expression_]: ../expressions.md
-[`Future::poll`]: https://doc.rust-lang.org/std/future/trait.Future.html#tymethod.poll
-[`Context`]: https://doc.rust-lang.org/std/task/struct.Context.html
-[`Poll::Pending`]: https://doc.rust-lang.org/std/task/enum.Poll.html#variant.Pending
-[`Poll::Ready`]: https://doc.rust-lang.org/std/task/enum.Poll.html#variant.Ready
+[`Future::poll`]: ../../std/future/trait.Future.html#tymethod.poll
+[`Context`]: ../../std/task/struct.Context.html
+[`Poll::Pending`]: ../../std/task/enum.Poll.html#variant.Pending
+[`Poll::Ready`]: ../../std/task/enum.Poll.html#variant.Ready
 
 > **Edition differences**: Await expressions are only available in Rust 2018.
 
@@ -39,8 +39,8 @@ current [async context] when the async context itself was
 polled. Because `await` expressions are only legal in an async
 context, there must be some task context available.
 
-[`Context`]: https://doc.rust-lang.org/std/task/struct.Context.html
-[async context]: ../expressions/block-expr.html#async-context
+[`Context`]: ../../std/task/struct.Context.html
+[async context]: ../expressions/block-expr.md#async-context
 
 ## Approximate desugaring