Update "User Guide"  TOC tree.
@@ -7,7 +7,7 @@ concepts and features, details can be found in the `API Reference <reference.htm
.. toctree::
:maxdepth: 1
- Installation Guide <https://www.colour-science.org/installation-guide>
+ Installation <https://www.colour-science.org/installation-guide>
tutorial
how-to
basics
