[Docs] mention CMake version in tips-and-tricks.rst

Author: tttapa

doxygen/sphinx/source/usage/tips-and-tricks.rst

@@ -196,9 +196,14 @@ To delete all cached problems, use:
     alpaqa cache clean
 
 For the compilation of C code generated by CasADi, |pylib_name| relies on
-`CMake <https://cmake.org/cmake/help/latest>`_. If you want to change the
-compiler or the options used, you can clean |pylib_name|'s CMake build directory
-and then set the appropriate environment variables, for example:
+`CMake <https://cmake.org/cmake/help/latest>`_. Version 3.17 or later is
+required: by default, a recent version of CMake will be installed into your
+Python virtual environment when you install |pylib_name|. To use a different
+version of CMake, you can set the ``ALPAQA_CMAKE_PROGRAM`` environment variable.
+
+If you want to change the compiler or the options used, you can clean
+|pylib_name|'s CMake build directory and then set the appropriate environment
+variables, for example:
 
 .. code-block:: bash