doc: Fix the tutorial's link to rustpkg docs

Author: blake2-ppc

doc/tutorial.md

@@ -2979,15 +2979,15 @@ tutorials on individual topics.
 * [The foreign function interface][ffi]
 * [Containers and iterators](tutorial-container.html)
 * [Error-handling and Conditions](tutorial-conditions.html)
-* [Packaging up Rust code](rustpkg)
+* [Packaging up Rust code][rustpkg]
 
 There is further documentation on the [wiki], however those tend to be even more out of date as this document.
 
 [borrow]: tutorial-borrowed-ptr.html
 [tasks]: tutorial-tasks.html
 [macros]: tutorial-macros.html
 [ffi]: tutorial-ffi.html
-[rustpkg]: tutorial-rustpkg.html
+[rustpkg]: rustpkg.html
 
 [wiki]: https://github.com/mozilla/rust/wiki/Docs