python: add directory structure README.rst files

Add short readmes to python/, python/qemu/, python/qemu/machine,
python/qemu/qmp, and python/qemu/utils that explain the directory
hierarchy. These readmes are visible when browsing the source on
e.g. gitlab/github and are designed to help new developers/users quickly
make sense of the source tree.

They are not designed for inclusion in a published manual.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-13-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/README.rst

@@ -0,0 +1,41 @@
+QEMU Python Tooling
+===================
+
+This directory houses Python tooling used by the QEMU project to build,
+configure, and test QEMU. It is organized by namespace (``qemu``), and
+then by package (e.g. ``qemu/machine``, ``qemu/qmp``, etc).
+
+``setup.py`` is used by ``pip`` to install this tooling to the current
+environment. ``setup.cfg`` provides the packaging configuration used by
+``setup.py`` in a setuptools specific format. You will generally invoke
+it by doing one of the following:
+
+1. ``pip3 install .`` will install these packages to your current
+   environment. If you are inside a virtual environment, they will
+   install there. If you are not, it will attempt to install to the
+   global environment, which is **not recommended**.
+
+2. ``pip3 install --user .`` will install these packages to your user's
+   local python packages. If you are inside of a virtual environment,
+   this will fail; you likely want the first invocation above.
+
+If you append the ``-e`` argument, pip will install in "editable" mode;
+which installs a version of the package that installs a forwarder
+pointing to these files, such that the package always reflects the
+latest version in your git tree.
+
+See `Installing packages using pip and virtual environments
+<https://packaging.python.org/guides/installing-using-pip-and-virtual-environments/>`_
+for more information.
+
+
+Files in this directory
+-----------------------
+
+- ``qemu/`` Python package source directory.
+- ``PACKAGE.rst`` is used as the README file that is visible on PyPI.org.
+- ``README.rst`` you are here!
+- ``VERSION`` contains the PEP-440 compliant version used to describe
+  this package; it is referenced by ``setup.cfg``.
+- ``setup.cfg`` houses setuptools package configuration.
+- ``setup.py`` is the setuptools installer used by pip; See above.