Fix #1879

I'm not used to rst and I'm not sure that the `:mod:` notacion (extracted from [collective.developermanual](https://github.com/collective/collective.developermanual/blob/master/source/reference_manuals/active/writing/writing.rst#other-sphinx-and-restructured-text-source-snippets)) was correct. If it's wrong, please tell me how to fix it.