Add Nutils to list of available solvers (#213)

Author: davidscn

flow-over-heated-plate/README.md

@@ -31,6 +31,8 @@ Solid participant:
 
 * FEniCS. For more information, have a look at the [FeniCS adapter documentation](https://www.precice.org/adapter-fenics.html).
 
+* Nutils. For more information, have a look at the [Nutils adapter documentation](https://precice.org/adapter-nutils.html).
+
 ## Running the Simulation
 
 All listed solvers can be used in order to run the simulation. Open two separate terminals and start the desired fluid and solid participant by calling the respective run script `run.sh` located in the participant directory. For example: