doc/overview: remove Installation section

This is a leftover installation section with outdated info. Remove it completely
since the installation has been moved to the "Getting Started" section.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>

doc/overview.rst

@@ -1,45 +1,6 @@
 Overview
 ========
 
-Installation
-------------
-
-The default installation is available via PyPI:
-
-.. code-block:: bash
-
-    $ pip install labgrid
-
-or by cloning the repository and installing manually:
-
-.. code-block:: bash
-
-    $ git clone https://github.com/labgrid-project/labgrid
-    $ cd labgrid && python3 setup.py install
-
-Extra Requirements
-~~~~~~~~~~~~~~~~~~
-Labgrid supports different extras:
-
-- onewire: install onewire support, requires ``onewire>=0.0.2`` from PyPI and
-  additionally ``libow-dev`` on Debian based distributions.
-- coordinator: installs required depencies to start a crossbar coordinator
-
-The extras can be selected by passing them after the package name in square
-brackets:
-
-.. code-block:: bash
-
-    $ pip install labgrid[onewire]
-
-or to enable both:
-
-.. code-block:: bash
-
-    $ pip install labgrid[onewire,coordinator]
-
-Depending on the used shell settings, the brackets may have to be escaped via ``\``.
-
 Architecture
 ------------