feat(info): indicate OpenAPI 2.0 definition version (#9167)

src/core/components/openapi-version.jsx

@@ -0,0 +1,15 @@
+import React from "react"
+import PropTypes from "prop-types"
+
+
+const OpenAPIVersion = ({ oasVersion }) => (
+  <small className="version-stamp">
+    <pre className="version">OAS {oasVersion}</pre>
+  </small>
+)
+
+OpenAPIVersion.propTypes = {
+  oasVersion: PropTypes.string.isRequired
+}
+
+export default OpenAPIVersion