Do not write to local disk in notebook 00

[Zeitsperre]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes a portion of https://github.com/Ouranosinc/pavics-jupyter-env-issues/issues/23
• (If applicable) Documentation has been added / updated (for bug fixes / features).
• (If applicable) Tests have been added.
• CHANGELOG.rst has been updated (with summary of main changes).
  • Link to issue (:issue:number) and pull request (:pull:number) has been added.

What kind of change does this PR introduce?

• Slightly modified 00_Introduction_to_JupyterLab.ipynb to not write to disk.

Does this PR introduce a breaking change?

Not in my opinion. The example Markdown has been modified to suggest that users can write to their workspaces by modifying the example.

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[coveralls]

coverage: 82.055%. remained the same
when pulling 9a6ae9f on fix-pjeiv-23
into 97e5163 on master.

[tlvu]

NB pass in a read-only current dir now, thanks.