docs: drop documentation for installing without virtualenv

Installing globally as root require an unjustified trust in our build/install
process ... and makes it very hard to uninstall or clean up.

Installing as a user is slightly better but also more error-prone and not
recommended.

Those who really want to do it and know how to do it also don't need this
description.

docs/installation.rst

@@ -1,163 +1,142 b''
 .. _installation:
 
 ==========================
 Installation on Unix/Linux
 ==========================
 
 The following describes three different ways of installing Kallithea:
 
 - :ref:`installation-source`: The simplest way to keep the installation
   up-to-date and track any local customizations is to run directly from
   source in a Kallithea repository clone, preferably inside a virtualenv
   virtual Python environment.
 
 - :ref:`installation-virtualenv`: If you prefer to only use released versions
   of Kallithea, the recommended method is to install Kallithea in a virtual
   Python environment using `virtualenv`. The advantages of this method over
   direct installation is that Kallithea and its dependencies are completely
   contained inside the virtualenv (which also means you can have multiple
   installations side by side or remove it entirely by just removing the
   virtualenv directory) and does not require root privileges.
 
-- :ref:`installation-without-virtualenv`: The alternative method of installing
-  a Kallithea release is using standard pip. The package will be installed in
-  the same location as all other Python packages you have ever installed. As a
-  result, removing it is not as straightforward as with a virtualenv, as you'd
-  have to remove its dependencies manually and make sure that they are not
-  needed by other packages.
+- Kallithea can also be installed with plain pip - globally or with ``--user``
+  or similar. The package will be installed in the same location as all other
+  Python packages you have ever installed. As a result, removing it is not as
+  straightforward as with a virtualenv, as you'd have to remove its
+  dependencies manually and make sure that they are not needed by other
+  packages. We recommend using virtualenv.
 
 Regardless of the installation method you may need to make sure you have
 appropriate development packages installed, as installation of some of the
 Kallithea dependencies requires a working C compiler and libffi library
 headers. Depending on your configuration, you may also need to install
 Git and development packages for the database of your choice.
 
 For Debian and Ubuntu, the following command will ensure that a reasonable
 set of dependencies is installed::
 
     sudo apt-get install build-essential git libffi-dev python3-dev
 
 For Fedora and RHEL-derivatives, the following command will ensure that a
 reasonable set of dependencies is installed::
 
     sudo yum install gcc git libffi-devel python3-devel
 
 .. _installation-source:
 
 
 Installation from repository source
 -----------------------------------
 
 To install Kallithea in a virtualenv using the stable branch of the development
 repository, use the following commands in your bash shell::
 
         hg clone https://kallithea-scm.org/repos/kallithea -u stable
         cd kallithea
         python3 -m venv venv
         . venv/bin/activate
         pip install --upgrade pip setuptools
         pip install --upgrade -e .
         python3 setup.py compile_catalog   # for translation of the UI
 
 .. note::
    This will install all Python dependencies into the virtualenv. Kallithea
    itself will however only be installed as a pointer to the source location.
    The source clone must thus be kept in the same location, and it shouldn't be
    updated to other revisions unless you want to upgrade. Edits in the source
    tree will have immediate impact (possibly after a restart of the service).
 
 You can now proceed to :ref:`install-front-end`.
 
 .. _installation-virtualenv:
 
 
 Installing a released version in a virtualenv
 ---------------------------------------------
 
 It is highly recommended to use a separate virtualenv for installing Kallithea.
 This way, all libraries required by Kallithea will be installed separately from your
 main Python installation and other applications and things will be less
 problematic when upgrading the system or Kallithea.
 An additional benefit of virtualenv is that it doesn't require root privileges.
 
 - Don't install as root - install as a dedicated user like ``kallithea``.
   If necessary, create the top directory for the virtualenv (like
   ``/srv/kallithea/venv``) as root and assign ownership to the user.
 
   Make a parent folder for the virtualenv (and perhaps also Kallithea
   configuration and data files) such as ``/srv/kallithea``. Create the
   directory as root if necessary and grant ownership to the ``kallithea`` user.
 
 - Create a new virtual environment, for example in ``/srv/kallithea/venv``,
   specifying the right Python binary::
 
     python3 -m venv /srv/kallithea/venv
 
 - Activate the virtualenv in your current shell session and make sure the
   basic requirements are up-to-date by running the following commands in your
   bash shell::
 
     . /srv/kallithea/venv/bin/activate
     pip install --upgrade pip setuptools
 
 .. note:: You can't use UNIX ``sudo`` to source the ``activate`` script; it
    will "activate" a shell that terminates immediately.
 
 - Install Kallithea in the activated virtualenv::
 
     pip install --upgrade kallithea
 
 .. note:: Some dependencies are optional. If you need them, install them in
    the virtualenv too::
 
      pip install --upgrade kallithea python-ldap python-pam psycopg2
 
    This might require installation of development packages using your
    distribution's package manager.
 
    Alternatively, download a .tar.gz from http://pypi.python.org/pypi/Kallithea,
    extract it and install from source by running::
 
      pip install --upgrade .
 
 - This will install Kallithea together with all other required
   Python libraries into the activated virtualenv.
 
 You can now proceed to :ref:`install-front-end`.
 
-.. _installation-without-virtualenv:
-
-
-Installing a released version without virtualenv
-------------------------------------------------
-
-For installation without virtualenv, 'just' use::
-
-    pip install kallithea
-
-Note that this method requires root privileges and will install packages
-globally without using the system's package manager.
-
-To install as a regular user in ``~/.local``, you can use::
-
-    pip install --user kallithea
-
-You can now proceed to :ref:`install-front-end`.
-
-.. _install-front-end:
-
 
 Prepare front-end files
 -----------------------
 
 Finally, the front-end files with CSS and JavaScript must be prepared. This
 depends on having some commands available in the shell search path: ``npm``
 version 6 or later, and ``node.js`` (version 12 or later) available as
 ``node``. The installation method for these dependencies varies between
 operating systems and distributions.
 
 Prepare the front-end by running::
 
     kallithea-cli front-end-build
 
 You can now proceed to :ref:`setup`.