Fix README relative link.

README.md

@@ -51,7 +51,7 @@ features = ["c"]
 
 ## Contributing
 
-1. Pick one or more intrinsics from the [pending list][#progress].
+1. Pick one or more intrinsics from the [pending list](#progress).
 2. Fork this repository
 3. Port the intrinsic(s) and their corresponding [unit tests][1] from their [C implementation][2] to
    Rust.