Fix Sphinx warning in doc building for pig-004.rst
@@ -82,7 +82,7 @@ mechamism to remove outputs from notebooks in the Github repository.
In the process of documentation building the notebooks will be texted and executed
automatically, so the static HTML-formatted notebooks will contain output cells
rendered in the the documentation. On the contrary, links to Binder notebooks and
-download links to *.ipynb files will point to empty-output notebooks.
+download links to .ipynb files will point to empty-output notebooks.
To solve the versioning issue for datasets, we propose to only use stable
example datasets. Examples are `gammapy-fermi-lat-data`_ or
