Update install instructions

Closes #7

README.rst

@@ -31,21 +31,21 @@ The install procedure is performed as follows:
 
 .. code-block:: shell
 
-    $ python setup.py install
+    $ pip install .
 
-If you need to install the module in the user folder :
+If you need to install the module in the user folder:
 
 .. code-block:: shell
 
-    $ python setup.py install --user
+    $ pip install . --user
 
 To run the tests:
 
 .. code-block:: shell
 
     $ pytest
 
-Finally to build the documentation, you should invoke the `build_sphinx` option :
+Finally to build the documentation, you should invoke the `build_sphinx` option:
 
 .. code-block:: shell