Update README

Python/README.txt → Python/README.md

@@ -3,35 +3,25 @@ The C++ wrappers for the QuantLib-Python extension module are created
 by means of SWIG (Simplified Wrapper and Interface Generator)
 available from <http://www.swig.org/>; the latest version is suggested.
 
-Building the wrappers requires the Setuptools package.
+Building the wrappers requires the `setuptools` and `build` packages;
+both can be installed (preferably in a virtual environment) by means
+of `pip install`.
 
 Generating the wrappers is not required if you are using a distributed
 tarball. If you're building from a Git checkout, instead, use the
-command:
-
-    python setup.py wrap
-
-The commands to be issued for building and testing the
-wrappers are:
-
-    python setup.py build
-    python setup.py test
-
-respectively.
+command `swig.cmd` on Windows or `make` on other platforms.  Running
+`make` also builds the wrappers as a wheel; on Windows, this requires
+the explicit command `python -m build --wheel` instead.
 
 The build step requires that the QuantLib headers and library can be
 found by the compiler. On Unix-like platforms, this requires that
 `quantlib-config` is in your path. On the Windows platform, instead,
 it requires you to define a `QL_DIR` environment variable pointing to
 your QuantLib directory (e.g., `C:\Lib\QuantLib`.)
 
-The suggested way to install the module is to run first
-
-    python setup.py bdist_wheel
+Once built, the resulting wheel can be installed with `pip`.
 
-which requires the wheel module to be available and which will create
-a QuantLib wheel in the dist folder.  The resulting wheel can then
-be installed with pip in the desired environment.
+Finally, testing the wheel requires `tox`, also available via
+`pip install`.  Once available, running `tox run` will run the
+test suite.
 
-The test suite is implemented on top of the PyUnit framework, which is
-included in the Python standard library.