Improved documentation: BibTex citations and structure by categories (#386)

Co-authored-by: Michael Denker <[email protected]>

Author: dizcza

.gitignore

@@ -45,7 +45,7 @@ lib
 lib64
 # sphinx build directory
 doc/_build
-doc/reference/toctree/*
+doc/reference/_toctree
 *.h5
 # setup.py dist directory
 dist

doc/authors.rst

@@ -1,5 +1,3 @@
-.. _authors:
-
 ************************
 Authors and contributors
 ************************
@@ -8,9 +6,6 @@ The following people have contributed code and/or ideas to the current version
 of Elephant. The institutional affiliations are those at the time of the
 contribution, and may not be the current affiliation of a contributor.
 
-Do you want to contribute to Elephant? Please refer to the
-:ref:`developers_guide`.
-
 * Alper Yegenoglu [1]
 * Andrew Davison [2]
 * Björn Müller [1]