[Doc] fix labs

doc/Doxyfile.extra.in

doc/d-labs/1-directgeom.md

doc/d-labs/2-invgeom.md

doc/d-labs/3-invkine.md

doc/d-labs/4-dyn.md

doc/d-labs/5-planner.md

doc/d-labs/6-wpg.md

doc/d-labs/7-learn.md

doc/d-labs/src/continuous.py

doc/d-labs/src/display.py

doc/d-labs/src/dpendulum.py

doc/d-labs/src/factor.py

doc/d-labs/src/foot_steps.py

doc/d-labs/src/graph.py

doc/d-labs/src/mobilerobot.py

doc/d-labs/src/ocp.py

doc/d-labs/src/pendulum.py

doc/d-labs/src/prm_display.py

doc/d-labs/src/qnet.py

doc/d-labs/src/qtable.py