Add link to CI example.

Can update later when this has moved to Gitlab.

README.rst

@@ -167,8 +167,10 @@ The compilation of the ``*-mpi`` toolchains needs linux headers installed. (TODO
 Working example
 ~~~~~~~~~~~~~~~
 
-We have a continuous integration example at XXX, that shows the complete
-compilation cycle (including compilation of Octopus). (TODO)
+There is an
+[example](https://github.com/mpsd-computational-science/octopus-with-mpsd-software)
+compilation that shows the complete compilation cycle (including compilation of
+Octopus) using the ``foss2022a-serial`` toolchain.