definition -> document
MODIFY
guidelines/v2.0/EXTENSIONS.md
guidelines/v2.0/EXTENSIONS.md
# OpenAPI Extensions
-The OpenAPI Specification version 2.0 allows for custom properties to be added at several places within an OpenAPI definition, allowing
+The OpenAPI Specification version 2.0 allows for custom properties to be added at several places within an OpenAPI document., allowing
API providers to extend the meta-data provided for their REST APIs as needed. Extension properties are always
prefixed by "x-" and can have any valid JSON format value.

definition -> document