Add documentation for the diff command

Author: NyanKiyoshi

docs/_static/diff_results.png

@@ -0,0 +1,4 @@
+.. _diff_usage:
+
+The Diff Command
+----------------

docs/diff.rst

@@ -53,12 +53,18 @@ Quick Start
         | module3 |                         |
         +---------+-------------------------+
 
-4. Or for a nicer presentation, use ``django-queries html > results.txt`` to export the results as HTML. See `this example <./html_export_results.html>`_ for a demo!
+4. Or for a nicer presentation, use ``django-queries html > results.html`` to export the results as HTML. See `this example <./html_export_results.html>`_ for a demo!
 
     .. image:: _static/html_export_results.png
         :width: 500 px
         :align: center
 
+5. By running it twice with the option described :ref:`here <diff_usage>` and by running ``django-queries diff`` you will get something like this:
+
+    .. image:: _static/diff_results.png
+        :width: 500 px
+        :align: center
+
 
 Getting Help
 ============
@@ -76,6 +82,7 @@ More Topics
 .. toctree::
     :maxdepth: 2
 
+    diff
     customize
     usage
     contributing

docs/index.rst

@@ -39,3 +39,17 @@ The SHOW Command
     View a given rapport.
 
     Options: none
+
+
+The DIFF Command
+++++++++++++++++
+
+.. code-block:: text
+
+    Usage: django-queries diff [OPTIONS] [LEFT_FILE] [RIGHT_FILE]
+
+    Render the diff as a console table with colors.
+
+    Options: none
+
+:ref:`More details on how to use the diff command properly. <diff_usage>`