feat(spec): JSON Schema 2020-12 definition for Arazzo descriptions

closes #176

schemas/v1.0/dialect/base.schema.yaml

@@ -0,0 +1,21 @@
+$id: https://spec.openapis.org/arazzo/1.0/dialect/base
+$schema: https://json-schema.org/draft/2020-12/schema
+title: Arazzo 1.0 Schema Object Dialect
+description: |-
+  A JSON Schema dialect describing schemas found in
+  OpenAPI Initiative Arazzo documents
+
+$dynamicAnchor: meta
+
+$vocabulary:
+  https://json-schema.org/draft/2020-12/vocab/core: true
+  https://json-schema.org/draft/2020-12/vocab/applicator: true
+  https://json-schema.org/draft/2020-12/vocab/unevaluated: true
+  https://json-schema.org/draft/2020-12/vocab/validation: true
+  https://json-schema.org/draft/2020-12/vocab/meta-data: true
+  https://json-schema.org/draft/2020-12/vocab/format-annotation: true
+  https://json-schema.org/draft/2020-12/vocab/content: true
+  https://spec.openapis.org/oas/3.1/vocab/base: false
+
+allOf:
+  - $ref: https://json-schema.org/draft/2020-12/schema

schemas/v1.0/schema-base.yaml

@@ -0,0 +1,17 @@
+$id: 'https://spec.openapis.org/arazzo/1.0/schema-base/2024-08-01'
+$schema: 'https://json-schema.org/draft/2020-12/schema'
+description: |-
+  The description of OpenAPI Initiative Arazzo v1.0.0 documents using the
+  Arazzo JSON Schema dialect, as defined by https://spec.openapis.org/arazzo/v1.0.0
+
+$ref: 'https://spec.openapis.org/arazzo/1.0/schema/2024-08-01'
+
+type: object
+properties:
+  jsonSchemaDialect:
+    $ref: '#/$defs/dialect'
+unevaluatedProperties: false
+
+$defs:
+  dialect:
+    const: 'https://spec.openapis.org/arazzo/1.0/dialect/base'