Replace one last reference to pull/584 with a real CLI docs link (#603)

content/master/concepts/composition-functions.md

@@ -422,7 +422,7 @@ To write a composition function, you:
 1. [Test the function](#test-a-composition-that-uses-functions).
 1. Build the function, and push it to a package registry.
 
-You use the [Crossplane CLI](https://github.com/crossplane/docs/pull/584) to
+You use the [Crossplane CLI]({{<ref "../cli">}}) to
 create, test, build, and push a function. For example,
 
 ```shell {copy-lines=none}