should add spec/comments/proposals/changes to implement for v0.1.0

[hoatle]

so that v0.1.0 is good enough for other extensions to use.

It's best if other extensions can configure their validators via simple ruby code to provide 1 or more (schema, data) pairs to validate, the static schema can be loaded via yaml files (the abstract, complex helper APIs are provided by this extension to leverage https://github.com/ruby-json-schema/json-schema).

For full control of validators, extensions can implement the validate or validate_common, validate_node methods of the validators