Prefer doc role to ref role.

Co-authored-by: Sviatoslav Sydorenko <wk.cvs.github@sydorenko.org.ua>

docs/userguide/index.rst

@@ -16,7 +16,7 @@ Transition to PEP517
 Since setuptools no longer serves as the default build tool, one must explicitly
 opt in (by providing a :file:`pyproject.toml` file) to use this library. The user
 facing part is provided by tools such as pip and
-backend interface is described :ref:`in this document <../build_meta>`. The
+backend interface is described :doc:`in this document <../build_meta>`. The
 quickstart provides an overview of the new workflow.
 
 .. toctree::