update documented value in README to match 5.* breaking change

closes #391

README.md

@@ -162,7 +162,7 @@ This piece of middleware validates the contents of the response received from up
 |raise| false | false | Raise an exception on error instead of responding with a generic error body. |
 |validate_success_only| true | false | Also validate non-2xx responses only. |
 |ignore_error| false | false | Validate and ignore result even if validation is error. So always return original data. |
-|parse_response_by_content_type| false | false | Parse response body to JSON only if Content-Type header is 'application/json'. When false, this always optimistically parses as JSON without checking for Content-Type header. |
+|parse_response_by_content_type| true | true | Parse response body to JSON only if Content-Type header is 'application/json'. When false, this always optimistically parses as JSON without checking for Content-Type header. |
 |strict| false | false | Puts the middleware into strict mode, meaning that response code and content type does not defined in the schema will be responded to with a 500 instead of application's status code. |
 |strict_reference_validation| always false | false | Raises an exception (`OpenAPIParser::MissingReferenceError`) on middleware load if the provided schema file contains unresolvable references (`$ref:"#/something/not/here"`). Not supported on Hyper-schema parser. Defaults to `false` on OpenAPI3 but will default to `true` in next major version. |