3.7.2 - Fix pypy support and add pypy documentation

https://github.com/elastic/elasticsearch-dsl-py/blob/master/Changelog.rst#620-2018-07-03

https://github.com/elastic/elasticsearch-dsl-py/issues/953

docs/index.rst

@@ -249,6 +249,57 @@ Or, install the latest development release directly from GitHub:
     substitute ``pip`` as an administrator in place of ``sudo pip3``, in the
     above commands.
 
+
+Installation using pypy3
+------------------------
+
+For the best possible processing speed, consider using `parsedmarc` inside a ``pypy3``
+virtualenv. First, `download the latest version of pypy3`_. Extract it to
+``/opt/pypy3`` (``sudo mkdir /opt`` if ``/opt`` does not exist), then create a
+symlink:
+
+.. code-block:: bash
+
+    $ sudo ln -s /opt/pypy3/bin/pypy3 /usr/local/bin/pypy3
+
+Install ``virtualenv`` on your system:
+
+.. code-block:: bash
+
+    $ sudo apt-get install python3-pip
+    $ sudo -H pip3 install -U virtualenv
+
+Uninstall any instance of ``parsedmarc`` that you may have installed globally
+
+.. code-block:: bash
+
+    $ sudo -H pip3 uninstall -y parsedmarc
+
+Next, create a ``pypy3`` virtualenv for parsedmarc
+
+
+.. code-block:: bash
+
+    $ sudo mkdir /opt/venvs
+    $ cd /opt/venvs
+    $ sudo -H pip3 install -U virtualenv
+    $ sudo virtualenv --download -p /usr/local/bin/pypy3 parsedmarc
+    $ sudo -H /opt/venvs/parsedmarc/bin/pip3 install -U parsedmarc
+    $ sudo ln -s /opt/venvs/parsedmarc/bin/parsedmarc /usr/local/bin/parsedmarc
+
+To upgrade ``parsedmarc`` inside the virtualenv, run:
+
+
+.. code-block:: bash
+
+    $ sudo -H /opt/venvs/parsedmarc/bin/pip3 install -U parsedmarc
+
+Or, install the latest development release directly from GitHub:
+
+.. code-block:: bash
+
+    $ sudo -H /opt/venvs/parsedmarc/bin/pip3 install -U git+https://github.com/domainaware/parsedmarc.git
+
 Optional dependencies
 ---------------------
 
@@ -549,6 +600,16 @@ Use this command to check the status of the service:
 
     sudo service parsedmarc status
 
+.. warning::
+
+    Always restart the service every time you upgrade to a new version of
+    ``parsedmarc``:
+
+   .. code-block:: bash
+
+       sudo service parsedmarc restart
+
+
 Using the Kibana dashboards
 ===========================
 
@@ -720,6 +781,8 @@ Indices and tables
 
 .. _Demystifying DMARC: https://seanthegeek.net/459/demystifying-dmarc/
 
+.. _download the latest version of pypy3: https://pypy.org/download.html#default-with-a-jit-compiler
+
 .. _X-Pack: https://www.elastic.co/products/x-pack
 
 .. _kibana_saved_objects.json: https://raw.githubusercontent.com/domainaware/parsedmarc/master/kibana/kibana_saved_objects.json