Merge branch 'setup-for-ci' into 'master'

.gitlab-ci.yml

README.md

docs/source/conf.py

docs/source/index.rst

docs/source/intake.rst

docs/source/quality.rst

docs/source/tutorial_esmvaltool.ipynb

docs/source/tutorial_intake-1-3-dkrz-catalogs-era5.ipynb

docs/source/tutorials.rst

notebooks/clear_and_prepare_for_ci.ipynb

notebooks/demo/tutorial_data-quality_atmodat-checker.ipynb

notebooks/demo/tutorial_esmvaltool.ipynb

notebooks/demo/tutorial_intake-1-3-dkrz-catalogs-era5.ipynb

notebooks/demo/tutorial_intake-1-introduction.ipynb

notebooks/demo/tutorial_intake-2-subset-catalogs.ipynb

notebooks/demo/tutorial_intake-3-merge-catalogs.ipynb

...s/demo/tutorial_intake-4-preprocessing-derived-vars.ipynb

...o/use-case_advanced_summer_days_intake_xarray_cmip6.ipynb

...o/use-case_calculate-frost-days_intake-xarray_cmip6.ipynb

notebooks/demo/use-case_climate-extremes-indices_cdo.ipynb