Add some acknowledgements.

Author: kpeeters

web2/cadabra2/source/people.html

@@ -19,8 +19,11 @@ <h2>Acknowledgements</h2>
 canonicalisation code), James Allen (for writing much of the original
 factoring code), Dominic Price (for the conversion to pybind, the
 Windows port and the logic that enables importing notebooks into other
-notebooks), the Software Sustainability Institute and the Institute
-of Advanced Study. Thanks to the many people who have sent me bug
+notebooks), Connor Behan (for patches to improve trace operators and
+various other parts), Leo Brewin (for writing beautiful tutorials),
+Mattia Scomparin (for contributing tutorial notebooks) the Software
+Sustainability Institute and the Institute of Advanced Study (for
+financial support). Thanks to the many people who have sent me bug
 reports (keep 'm coming), and thanks to all of you who use Cadabra,
 sent feedback or cited the Cadabra papers.
 </p>