Update versions/3.1.1.md

Author: ralfhandl

versions/3.1.1.md

@@ -210,7 +210,7 @@ Note that the `type` keyword allows `"integer"` as a value for convenience, but
 
 #### Data Type Format
 
-As defined by the [JSON Schema Validation specification](https://tools.ietf.org/html/draft-bhutton-json-schema-validation-00#section-7.3), data types can have an optional modifier property: `format`. As described in that specification, `format` is treated as a non-validating annotation by default; the ability to validate `format` varies across implementations.
+As defined by the [JSON Schema Validation specification](https://tools.ietf.org/html/draft-bhutton-json-schema-validation-00#section-7.3), data types can have an optional modifier keyword: `format`. As described in that specification, `format` is treated as a non-validating annotation by default; the ability to validate `format` varies across implementations.
 
 The OpenAPI Initiative also hosts a [Format Registry](https://spec.openapis.org/registry/format/) for formats defined by OAS users and other specifications. Support for any registered format is strictly OPTIONAL, and support for one registered format does not imply support for any others.