Reduce the size of /docs

[RondeauG]

Generic Issue

• xscen version: 0.7.1

Description

These two files/directories are currently pretty big and don't need to be.

• /docs/notebooks/samples/tutorial/ : ~ 8Mb
  • The files are already fairly small (4x4x18600, 1.3 Mb each), but could be reduced even further along the time axis.
• /docs/notebooks/samples/pangeo-cmip6.csv : ~ 8Mb.
  • This is basically only used once to show the advanced search features of search_data_catalogs. We don't need 35 000 assets to do that.

[Zeitsperre]

Can the pangeo-cmip6.csv be fetched from somewhere online? It's not the best practice (for PANGEO), but maybe we can simply point the test to that location?

[RondeauG]

Sadly not. It's based on an online version, but modified so the columns match ours.