Improve docs for JSON files

[andreoliwa]

Discussed in #480

^{Originally posted by benthevining March 30, 2022}
The docs and examples provide very little info about usage with JSON files. I see how I can require certain keys, but is that all nitpick can do? Can I require that certain keys are set to specific values?

• Document contains_json:

  nitpick/src/nitpick/resources/any/commitlint.toml

  Lines 5 to 12 in d9d5055

  	["package.json".contains_json]
  	commitlint = """
  	{
  	"extends": [
  	"@commitlint/config-conventional"
  	]
  	}
  	"""

• Document contains_keys:
  

  nitpick/src/nitpick/resources/javascript/package-json.toml

  Lines 5 to 6 in d9d5055

  	["package.json"]
  	contains_keys = ["name", "version", "repository.type", "repository.url", "release.plugins"]

• Write a ticket to document the unwritten plan:

  • To make the JSON plugin as flexible as the YAML (which was written recently).
  • Deprecate contains_keys in favour of Enforce presence of keys (with any values) #218
  • Deprecate contains_json in favour of configuring keys and nested objects like the YAML plugin does
  • That is a bit of work, and I don't know what is the demand for it now.