Broken links to new EUMETSAT website

[gerritholl]

Describe the bug

In various places in satpy there are broken links to the new EUMETSAT website. For example, the documentation for the seviri_l1b_hrit contains a broken link to the level 1.5 fileformat description on the EUMETSAT website.

To Reproduce

• Navigate to https://satpy.readthedocs.io/en/stable/readers.html#introduction
• Click on the link with the anchor MSG Level 1.5 Image Format Description
• Observe Error 404

Expected behavior

I expect that the link connects me with the image format description.

Actual results

In reality I get 404 - Page not found.

Additional context

Arguably this bug in in the EUMETSAT website because cool URIs dont change, but regrettably it's going to be up to pytroll to update the link.

We should probably search through all the docs and source code of all pytroll packages for links to the EUMETSAT website to check and potentially update them all.

[helgaweb]

@gerritholl It also holds for link in the slstr_l1b reader

satpy/satpy/readers/slstr_l1b.py

Line 41 in a3774e1

# https://www.eumetsat.int/website/wcm/idc/idcplg?IdcService=GET_FILE&dDocName=PDF_S3A_PN_SLSTR_L1_06&RevisionSelectionMethod=LatestReleased&Rendition=Web

[ameraner]

The links in seviri_l1b_hrit, seviri_l1b_nc, seviri_base and _geos_area will be fixed with #1485 as that PR is already touching those files (I started fixing them before seeing this issue). But I'm sure there are more around! So maybe you can change this issue to be general about all EUM links?

[gerritholl]

@ameraner Done.