Migrate README and vignettes to Data Package v2

[peterdesmet]

• Update README v2 support
• Update README examples (no changes)
• Update frictionless.Rmd.orig and recompile
• Update data-package.Rmd documentation
• Update data-package.Rmd examples
• Update data-resource.Rmd documentation
• Update data-resource.Rmd examples
• Update table-dialect.Rmd documentation
• Update table-dialect.Rmd examples
• Update table-schema.Rmd documentation
• Update table-schema.Rmd examples

Changes:

• "Tabular Data Resource": https://specs.frictionlessdata.io/tabular-data-resource/ -> https://datapackage.org/standard/data-resource/#tabular