Model builder, latent infection process components and tutorials

docs/tutorials/.pages

@@ -2,6 +2,10 @@ nav:
   - getting_started.md
   - basic_renewal_model.md
   - custom_randomvariables.md
+  - building_multisignal_models.md
+  - observation_processes_counts.md
+  - observation_processes_measurements.md
+  - latent_hierarchical_infections.md
   - hospital_admissions_model.md
   - day_of_the_week.md
   - periodic_effects.md