Add microcircuit rate verification comments

pynest/examples/Potjans_2014/network_params.py

@@ -71,6 +71,9 @@ def get_exc_inh_matrix(val_exc, val_inh, num_pops):
     # necessary for the scaling of the network.
     # The values were obtained by running this PyNEST microcircuit without MPI,
     # 'local_num_threads' 4 and both 'N_scaling' and 'K_scaling' set to 1.
+    #
+    # Since these rates were only taken from one simulation, they alone are not sufficient for verification.
+    # For that, rates should be compared to mean values over multiple runs with different RNG seeds.
     "full_mean_rates": np.array([0.903, 2.965, 4.414, 5.876, 7.569, 8.633, 1.105, 7.829]),
     # connection probabilities (the first index corresponds to the targets
     # and the second to the sources)