Use a deviating dialect for one of the resources in `example_package`

[peterdesmet]

To indicate that a datapackage.json makes use of v2 Table Dialect features, one needs to define:

"dialect": {
  "$schema": "https://datapackage.org/profiles/2.0/tabledialect.json"
}

Currently, none of the resources in example_package define a dialect (they all use defaults). As a result, it will also use the default for the not-defined $schema, which is v1, thus blocking any testing of v2 features.

Solution: define the dialect for one of the resources in the example_package. I suggest "observations", with e.g. tab-based delimiter.

• [ ] Add a "dialect": {"delimiter": "\t"} to the observations resource in datapackage.json
• [ ] Update the files to use tabs
• [ ] Rename the files to observations_1.tsv and observations_2.tsv
• [ ] Update reference to these files in tests
• [ ] Run tests
• [ ] Update reference to these files in examples and vignettes (especially comments)