Add a "Developer" section in the documentation

[OliRom]

Currently, the documentation only explains how to install and use the package. However, it lacks information for developers — such as how to run tests, generate the documentation, or build the C++ components.

Here are some topics that should be added to a new "Developer" section:

• How to run the tests (both Python and C++) with coverage
• How to generate the documentation
• How to build the C++ library files used by Python
• How to benchmark the package and show the results