Add guidelines for PR reviews.

docs/contributing.rst

@@ -9,12 +9,11 @@ First of all: thank you!
 Contributions can be made in different ways, not only code!
 As we follow the `all-contributors`_ specification, any contribution will be recognised accordingly.
 
-The first thing you might want to do, is to have a look at the `contributor guide <contributorfile.html>`_ page as well as the `code of conduct <conduct.html>`_.
+Follow these steps to get started:
 
-The second thing is to check you have ``git`` and ``pip`` installed in your system.
-
-The third thing is to install ``phys2bids`` as a developer.
-This will let you run the program with the latest modification, without requiring you to re-install it every time.
+1. Have a look at the `contributor guide <contributorfile.html>`_ page as well as the `code of conduct <conduct.html>`_.
+2. Make sure that you have a GitHub account. You can set up a `free GitHub account <https://github.com/>`_; here are some `instructions <https://help.github.com/articles/signing-up-for-a-new-github-account>`_.
+3. If you intend to contribute code and/or use the ``physiopy`` packages in any way, check that you have ``git`` and ``pip`` installed on your system. Then install ``phys2bids`` as a developer. This will let you run the program with the latest modification, without requiring to re-install it every time.
 
 .. _`all-contributors`: https://github.com/all-contributors/all-contributors
 
@@ -23,7 +22,6 @@ This will let you run the program with the latest modification, without requirin
     If it is, you might need to use ``pip`` instead of ``pip3``, although some OSs do adopt ``pip3`` anyway.
     If you want to check, type ``python --version`` in a terminal.
 
-
 Linux and mac developer installation
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