Metadata/tag support for fields in the schema

[draggeta]

I'm loving the performance of validx, but there is one thing that stops me from using it. For a project we need to be able to specify metadata (form doesn't matter, could be tags as well) for the schema on each level. We need to output this metadata if a field doesn't match.

An example would be that a value must be an Int between 10 and 20 and if it isn't, output the error as well as the metadata detailing it as non-critical.

I haven't been able to find anything like that in the docs, but I may be wrong.