Add an installation documentation.

docs/docs/installation.rst

@@ -0,0 +1,32 @@
+.. include:: ../global.rst
+
+Installation and Configuration
+==============================
+
+The preferred way
+-----------------
+
+On any system you can install |parso| directly from the Python package index
+using pip::
+
+    sudo pip install parso
+
+
+From git
+--------
+If you want to install the current development version (master branch)::
+
+    sudo pip install -e git://github.com/davidhalter/parso.git#egg=parso
+
+
+Manual installation from a downloaded package (not recommended)
+---------------------------------------------------------------
+
+If you prefer not to use an automated package installer, you can `download
+<https://github.com/davidhalter/parso/archive/master.zip>`__ a current copy of
+|parso| and install it manually.
+
+To install it, navigate to the directory containing `setup.py` on your console
+and type::
+
+    sudo python setup.py install