Improve install instructions: package name, commands, links & formatting

[gy-mate]

I set up Carto for amandasaurus/osm-mapping-party-before-after—this is an attempt to improve the install instructions to help anyone who wants to do the same.

Changes proposed in this pull request:

• Change order of dependencies
  • Usage dependencies first, then the development ones
• Correct yaml package name to pyyaml
• Update switch2osm.org link
• Add install command for Python packages per PEP 668
• Add link to ogr2ogr
• Add install & launch commands for Kosmtik
• Improve formatting

[imagico]

This looks fairly good, thanks for working on improving the documentation.

Some small things:

• we should not point to npm to install ogr2ogr - better point to https://gdal.org/en/latest/download.html
• python colormath in required not only for generate_road_colors.py but also for generate_unpaved_patterns.py - see Road color scripts depend on unmaintained colormath module #4922.
• i don't think we have any ruby code in the repository right now so ruby is not required IIRC.

[gy-mate]

@imagico All done!

[imagico]

That was fast. Looks all good to me now.