Recommend a specific config file to use and format user config as a w…

…arning.

doc/pip_and_pep_668.rst

@@ -28,15 +28,17 @@ Configure using pip.conf
 `Pip configuration files <pip-configuration>`_ can be used to set the desired behavior 
 Pip checks for global configuration files in ``XDG_CONFIG_DIRS``, as well as ``/etc/pip.conf``
 For details on ``XDG_CONFIG_DIRS`` refer to the `XDG base directories specification <xdg-base-dirs>`_.
-
-Creating a pip.conf in your user account's ``XDG_CONFIG_HOME`` (e.g. ``~/.config/pip/pip.conf``) does not appear to be sufficent when installing packages globally.
+If you're unsure which configuration file is in use by your system, ``/etc/pip.conf`` seems like the most generic.
 
 .. code-block:: ini
 
    [install]
    break-system-packages = true
 
 
+.. warning:: Creating a pip.conf in your user account's ``XDG_CONFIG_HOME`` (e.g. ``~/.config/pip/pip.conf``) does not appear to be sufficent when installing packages globally.
+
+
 Configuring for CI setup
 ------------------------