added documentation

backend/docs/_build/html/modules.html

backend/docs/_build/html/objects.inv

backend/docs/_build/html/petrinet.html

backend/docs/_build/html/py-modindex.html

backend/docs/_build/html/qagent.html

backend/docs/_build/html/search.html

backend/docs/_build/html/searchindex.js

backend/docs/_build/html/simplesimmodel.html

backend/docs/businessprocess.rst

backend/docs/case.rst

backend/docs/conf.py

backend/docs/dqn.rst

backend/docs/environment.rst

backend/docs/eventlog.rst

backend/docs/index.rst

backend/docs/make.bat

backend/docs/modules.rst

backend/docs/petrinet.rst

backend/docs/qagent.rst

backend/docs/simplesimmodel.rst