add merlin6 JB docs

docs/merlin6/jupyterhub/jupytext.md

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+# Jupytext - efficient editing
+
+[Jupytext](https://github.com/mwouts/jupytext) is a Jupyter serverextension
+that allows creating a text file from a notebook that can be kept in sync with
+it **with the aim of using more efficient editors or IDEs on it**. The file can
+be created in a number of formats, e.g. *markdown, *.py (light Script)*, and
+others. `Jupytext` will keep the both the notebook and this **paired** file in
+sync: If you save the paired file, changes will be carried over into the
+notebook, and vice versa. This pairing will persist also in new sessions of
+your notebook until you explicitely remove it again.
+
+The paired file contains only the cell contents and not the output. Therefore
+it also is **much better suited for revision control**, since the differences
+between versions are limited to the cells and these file formats yield more
+meaningful text differences than the default notebook storage format.
+
+## Creating a paired file in python format for efficient refactoring
+
+From your notebook, go to the `file` menu and navigate to the `jupytext`
+submenu. Select the **light script** pairing option. This will create a `*.py`
+file version with the same basename as your notebook file.
+
+![Jupytext menu](../../images/jupyter/jupytext_menu.png)
+/// caption
+///
+
+You can edit that file separately in your favourite python editor. The markdown
+text parts will be conserved in the file in the form of python comments.
+
+When you save the file and do a browser page reload of your jupyter notebook,
+you will see all the changes carried over into your jupyter notebook.
+
+## Creating a paired file in mardown format for efficient text authoring
+
+If you want to efficiently work on the descriptive text base of your notebook,
+just pair it using the `Pair notebook with Markdown` menu item and edit the
+generated `*.md` file with your favourite Markdown editor.
+
+## Disable autosaving when working  on the paired file
+
+Your notebooks usually auto save every 2 min (default). Turn this feature off
+when working with the paired file. Otherwise Jupyter will continue to save the
+state while you are editing the paired file, and the changes will be synced to
+the disk version of the paired file. You can disable the autosave by unchecking
+the `Autosave notebook` menu item in the Juytext menu (see above image).
+
+## Further information
+
+Please refer to:
+
+* [the Jupytext FAQ](https://jupytext.readthedocs.io/en/latest/faq.html)
+* [the Jupytext documentation](https://jupytext.readthedocs.io/en/latest/index.html)