DOC: remove "--user" flag from installation instructions

See #264.

Author: mgeier

CONTRIBUTING.rst

@@ -92,7 +92,7 @@ newest development version (a.k.a. "master") from Github_::
 
    git clone --recursive https://github.com/spatialaudio/python-sounddevice.git
    cd python-sounddevice
-   python3 -m pip install -e . --user
+   python3 -m pip install -e .
 
 .. _PyPI: https://pypi.org/project/sounddevice/
 .. _Github: https://github.com/spatialaudio/python-sounddevice/
@@ -118,7 +118,7 @@ If you make changes to the documentation, you can locally re-create the HTML
 pages using Sphinx_.
 You can install it and a few other necessary packages with::
 
-   python3 -m pip install -r doc/requirements.txt --user
+   python3 -m pip install -r doc/requirements.txt
 
 To (re-)build the HTML files, use::
 

doc/installation.rst

@@ -52,10 +52,10 @@ about :doc:`CONTRIBUTING`.
 
 To install the latest release from PyPI, use::
 
-   python3 -m pip install sounddevice --user
+   python3 -m pip install sounddevice
 
-If you want to install it system-wide for all users (assuming you have the
-necessary rights), you can just drop the ``--user`` option.
+Depending on your Python installation,
+you may have to use ``python`` instead of ``python3``.
 If you have installed the module already, you can use the ``--upgrade`` flag to
 get the newest release.