Added a bit more information to petab importer and objective function… (

#1126)

* Added a bit more information to petab importer and objective function created from petab. Line with "noqa" to keep url. Closes #1047

* Moved noqa somewhere else

* Apply suggestions from code review

Co-authored-by: Daniel Weindl <dweindl@users.noreply.github.com>

---------

Co-authored-by: Daniel Weindl <dweindl@users.noreply.github.com>

pypesto/petab/importer.py

@@ -61,11 +61,15 @@
 
 class PetabImporter(AmiciObjectBuilder):
     """
-    Importer for Petab files.
+    Importer for PEtab files.
 
     Create an `amici.Model`, an `objective.AmiciObjective` or a
-    `pypesto.Problem` from Petab files.
-    """
+    `pypesto.Problem` from PEtab files. The created objective function is a
+    negative log-likelihood function and can thus be negative. The actual
+    form of the likelihood depends on the noise model specified in the provided PEtab problem.
+    For more information, see
+    [the PEtab documentation](https://petab.readthedocs.io/en/latest/documentation_data_format.html#noise-distributions)
+    """  # noqa
 
     MODEL_BASE_DIR = "amici_models"