DOC: add BuDDy installation instructions

README.md

@@ -246,6 +246,27 @@ Currently, `download.py` expects to find Sylvan under `dd/sylvan` and built with
 (for an example, see `.travis.yml`).
 If the path differs in your environment, remember to update it.
 
+BuDDy can be downloaded and compiled as follows:
+
+```shell
+curl -L https://sourceforge.net/projects/buddy/files/buddy/BuDDy%202.4/buddy-2.4.tar.gz/download -o buddy-2.4.tar.gz
+tar -xzf buddy-2.4.tar.gz
+cd buddy-2.4/
+./configure  # as described in the README file of BuDDy
+make
+make install  # installs to `/usr/local/include/` and `/usr/local/lib/`
+# The installation location can be changed with `./configure --prefix=/where/to/install`
+
+pip uninstall -y dd
+python setup.py install --buddy  # passes `-lbdd` to the compiler
+```
+
+and the installation confirmed by invoking in another directory:
+
+```shell
+python -c "import dd.buddy"
+```
+
 
 Tests
 =====