docs rearrange

src/example_bouncing_ball/BouncingBall.mo

src/example_bouncing_ball/README.md

src/example_bouncing_ball/Simulate_BouncingBall.py

src/feature_model/feature_model.py

src/feature_model/modelica.g4

src/feature_model/modelicaLexer.py

src/feature_model/modelicaListener.py

src/feature_model/modelicaParser.py

src/feature_model/parse_modelica.py