Moving JupyterHub to access section

....tu-dresden.de/docs/access/desktop_cloud_visualization.md

doc.zih.tu-dresden.de/docs/access/jupyterhub.md

doc.zih.tu-dresden.de/docs/access/jupyterhub_for_teaching.md

doc.zih.tu-dresden.de/docs/access/login.md

doc.zih.tu-dresden.de/docs/access/web_vnc.md

...h.tu-dresden.de/docs/jobs_and_resources/alpha_centauri.md

doc.zih.tu-dresden.de/docs/jobs_and_resources/hpcda.md

doc.zih.tu-dresden.de/docs/software/data_analytics_with_r.md

doc.zih.tu-dresden.de/docs/software/deep_learning.md

...zih.tu-dresden.de/docs/software/get_started_with_hpcda.md

doc.zih.tu-dresden.de/docs/software/keras.md

doc.zih.tu-dresden.de/docs/software/py_torch.md

doc.zih.tu-dresden.de/docs/software/python.md

doc.zih.tu-dresden.de/docs/software/tensor_flow.md

...esden.de/docs/software/tensor_flow_on_jupyter_notebook.md

doc.zih.tu-dresden.de/docs/software/virtual_desktops.md

doc.zih.tu-dresden.de/mkdocs.yml