update the readme.md

Author: stevehu

README.md

@@ -10,7 +10,7 @@
 [![Build Status](https://travis-ci.org/networknt/json-schema-validator.svg?branch=master)](https://travis-ci.org/networknt/json-schema-validator) [![codecov.io](https://codecov.io/github/networknt/json-schema-validator/coverage.svg?branch=master)](https://codecov.io/github/networknt/json-schema-validator?branch=master)
 
 
-This is a Java implementation of the [JSON Schema Core Draft v4, v6, v7 and v2019-09](http://json-schema.org/latest/json-schema-core.html) specification for JSON schema validation. In addition, it also works for OpenAPI 3.0 request/response validation with some [configuration flags](doc/config.md). The default JSON parser is the [Jackson](https://github.com/FasterXML/jackson) that is the most popular one. As it is a key component in our [light-4j](https://github.com/networknt/light-4j) microservices framework to validate request/response against OpenAPI specification for [light-rest-4j](http://www.networknt.com/style/light-rest-4j/) and RPC schema for [light-hybrid-4j](http://www.networknt.com/style/light-hybrid-4j/) at runtime, performance is the most important aspect in the design. 
+This is a Java implementation of the [JSON Schema Core Draft v4, v6, v7, v2019-09 and v2020-12](http://json-schema.org/latest/json-schema-core.html) specification for JSON schema validation. In addition, it also works for OpenAPI 3.0 request/response validation with some [configuration flags](doc/config.md). For users who want to collect information from a JSON node based on the schema, the [walkers](doc/walkers.md) can help. The default JSON parser is the [Jackson](https://github.com/FasterXML/jackson) that is the most popular one. As it is a key component in our [light-4j](https://github.com/networknt/light-4j) microservices framework to validate request/response against OpenAPI specification for [light-rest-4j](http://www.networknt.com/style/light-rest-4j/) and RPC schema for [light-hybrid-4j](http://www.networknt.com/style/light-hybrid-4j/) at runtime, performance is the most important aspect in the design. 
 
 ## Why this library