add the doc/_build directory to gitignore
add the doc/_build directory to gitignore

agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,lukasjuhrich/pycroft,lukasjuhrich/pycroft,agdsn/pycroft