Resolve "Add suggested acknowledgements to the README"

Closes #253 (closed)

README.rst

 |pipeline status| |coverage report| |pypi| |conda| |version|
 
+=====
 Bilby
 =====
 
@@ -23,6 +24,46 @@ help in creating a merge request, see `this page
 <https://docs.gitlab.com/ee/gitlab-basics/add-merge-request.html>`__ or contact
 us directly. For advice on contributing, see `this help page <https://git.ligo.org/lscsoft/bilby/blob/master/CONTRIBUTING.md>`__.
 
+
+--------------
+Citation guide
+--------------
+
+If you use :code:`bilby` in a scientific publication, please cite
+
+* `Bilby: A user-friendly Bayesian inference library for gravitational-wave
+  astronomy
+  <https://ui.adsabs.harvard.edu/#abs/2018arXiv181102042A/abstract>`__
+
+Additionally, :code:`bilby` builds on a number of open-source packages. If you
+make use of this functionality in your publications, we recommend you cite them
+as requested in their associated documentation.
+
+**Samplers**
+
+* `dynesty <https://github.com/joshspeagle/dynesty>`__
+* `nestle <https://github.com/kbarbary/nestle>`__
+* `pymultinest <https://github.com/JohannesBuchner/PyMultiNest>`__
+* `cpnest <https://github.com/johnveitch/cpnest>`__
+* `emcee <https://github.com/dfm/emcee>`__
+* `ptemcee <https://github.com/willvousden/ptemcee>`__
+* `ptmcmcsampler <https://github.com/jellis18/PTMCMCSampler>`__
+* `pypolychord <https://github.com/vhaasteren/pypolychord>`__
+* `PyMC3 <https://github.com/pymc-devs/pymc3>`_
+
+
+**Gravitational-wave tools**
+
+* `gwpy <https://github.com/gwpy/gwpy>`__
+* `lalsuite <https://git.ligo.org/lscsoft/lalsuite>`__
+* `astropy <https://github.com/astropy/astropy>`__
+
+**Plotting**
+
+* `corner <https://github.com/dfm/corner.py>`__ for generating corner plot
+* `matplotlib <https://github.com/matplotlib/matplotlib>`__ for general plotting routines
+
+
 .. |pipeline status| image:: https://git.ligo.org/lscsoft/bilby/badges/master/pipeline.svg
    :target: https://git.ligo.org/lscsoft/bilby/commits/master
 .. |coverage report| image:: https://lscsoft.docs.ligo.org/bilby/coverage_badge.svg