Create list/gallery of datasets available in fetch

[mdtanker]

Description of the desired feature:

Automatically extract function from fetch to create either a list of datasets, or a gallery of thumbnails of the datasets.

To do:

• [ ] add notebooks for each below dataset
• [ ] add notebooks to docs/datasets/index.md
• [x] add note in fetch walkthrough

Datasets to add to gallery:

• [x] basement
• [x] bedmachine
• [x] bedmap2
• [x] bedmap_points
• [x] crustal_thickness
• [x] deepbedmap
• [x] etopo
• [x] geoid
• [ ] geomap
• [ ] ghf
• [ ] gia
• [ ] gravity
• [ ] groundingline
• [x] ibcso
• [x] ibcso_coverage
• [ ] ice_vel
• [x] imagery
• [ ] magnetics
• [ ] mass_change
• [ ] measures_boundaries
• [x] modis_moa
• [x] modis_mog
• [x] moho
• [x] rema
• [ ] rosetta_gravity
• [ ] rosetta_magnetics
• [x] sediment_thickness

Are you willing to help implement and maintain this feature?

Yes