add specification with example for entries in bib-file to documentati…

…on (NeuralEnsemble#504)

doc/contribute.rst

@@ -307,7 +307,31 @@ Citations
 The citations are in BibTeX format, stored in `doc/bib/elephant.bib
 <https://github.com/NeuralEnsemble/elephant/blob/master/doc/bib/elephant.bib>`_.
 
-To cite Elephant, refer to :doc:`citation`.
+Entries in the .bib are built according to the following specification:
+
+``{Last name of first author}+{last two digits of publication year}+"_"+{first page of article}``
+
+
+.. admonition:: Example
+
+    According to this specification, the following article:
+
+    S. Grün. Data-driven significance estimation of precise spike correlation. J. Neurophysiol., pages 1126–1140, 2009. doi:10.1152/jn.00093.2008.
+
+    is added to the .bib-file as ``Gruen09_1126``. The complete entry for this example is:
+
+    .. code-block:: rst
+
+        @article{Gruen09_1126,
+          title={Data-driven significance estimation of precise spike correlation},
+          author={Gr\"{u}n, S.},
+          year={2009},
+          journal={J. Neurophysiol.},
+          number={101},
+          pages={1126--1140},
+          doi={10.1152/jn.00093.2008}
+        }
+
 
 Each module in ``doc/reference`` folder ends with the reference section:
 
@@ -328,4 +352,6 @@ For example, ``:cite:'spade-Torre2013_132'`` will be rendered as ``sp1`` in
 the built HTML documentation, if ``<module name shortcut>`` is set to ``sp``
 and ``<module name>`` - to ``spade``.
 
+To cite Elephant itself, refer to :doc:`citation`.
+
 .. _Issue tracker: https://github.com/NeuralEnsemble/elephant/issues