Broken links

[tomneep]

Hi 👋 ,

I'm looking through the course and I've noticed that several of the links seem to be broken.

File	URL	Problem
index.md	https://xarray-spatial.org/	This goes somewhere weird, should this go to https://xarray-spatial.readthedocs.io/en/stable/ ?
index.md	https://sentinel.esa.int/web/sentinel/missions/sentinel-2	Can't find server
episodes/01-intro-raster-data.md	https://trac.osgeo.org/geotiff/	Should probably be updated to the GitHub link? https://github.com/OSGeo/libgeotiff
episodes/03-crs.md	https://foote.geography.uconn.edu/gcraft/notes/mapproj/mapproj_f.html	Can't find server
episodes/04-geo-landscape.md	https://cran.r-project.org/package=RQGIS	Removed from CRAN
episodes/04-geo-landscape.md	https://www.pitneybowes.com/us/location-intelligence/geographic-information-systems/mapinfo-pro.html	404
episodes/04-geo-landscape.md	https://boundlessgeo.com/	Can't find server
episodes/05-access-data.md	https://sentinel.esa.int/web/sentinel/missions/sentinel-2	Can't find server
episodes/06-raster-intro.md	https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-2-msi/msi-instrument	404
episodes/08-crop-raster-data.md	https://spacedata.copernicus.eu/collections/copernicus-digital-elevation-model	Taking a very long time to load, I'm not sure if it does eventually...
episodes/12-data-cube.md	https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm-overview	404
episodes/12-data-cube.md	https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm-overview	404

[fnattino]

@tomneep thank you so much for the detailed summary - fixes are on the way!