Move read_resource documentation to article

[peterdesmet]

The read_resource() documentation is very long, because it lists how all Data Resource properties are used. Cf. https://docs.ropensci.org/cffr/articles/crosswalk.html it might be good to move this info to an article and refer to it.

• List all ignore properties as separate headings (easier to reference)
• Make sure all field types have separate headings (easier to reference)
• In function descriptions, link to vignette("data-package") for Data Package
• In function descriptions, link to vignette("data-resource") for Data Resource
• In function descriptions, link to vignette("table-dialect") for CSV Dialect
• In function descriptions, link to vignette("table-schema") for Table Schema