schema: Set dialect, lint and validate data files

[kingthorin]

• Set the schema dialect to be 2020-12
• Add an example
• Add an overall description (happy to tweak this, I just threw some text in from the top of my head)
• Extended description from 500 to 550 because of Bootstrap.
• Simplified CPE pattern due to single errors in each of b, t, and w.
• Changed dom from oneOf to anyOf as it could be one or more, not simply one.

Checks done with:

• docker run --interactive --volume "$PWD:/workspace" ghcr.io/sourcemeta/jsonschema:v13.6.0 validate /workspace/schema.json /workspace/src/technologies/z.json
• docker run --interactive --volume "$PWD:/workspace" ghcr.io/sourcemeta/jsonschema:v13.6.0 lint /workspace/schema.json
• https://www.jsonschemavalidator.net/

This also leads me to the conclusion that existing checks/tests aren't checking/enforcing adherence to the schema.