Fix typo

Author: cramertj

src/SUMMARY.md

@@ -25,7 +25,7 @@
   - [`?` in `async` Blocks](07_workarounds/03_err_in_async_blocks.md)
   - [`Send` Approximation](07_workarounds/04_send_approximation.md)
   - [Recursion](07_workarounds/05_recursion.md)
-  - [`async` in Traits](07_workarounds/06_async_traits.md)
+  - [`async` in Traits](07_workarounds/06_async_in_traits.md)
 - [TODO: I/O](404.md)
   - [TODO: `AsyncRead` and `AsyncWrite`](404.md)
 - [TODO: Asynchronous Design Patterns: Solutions and Suggestions](404.md)