Update changelog and readme for release 4.2.0

Author: YstiaBot

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Yorc Changelog
 
-## UNRELEASED
+## 4.2.0 (September 10, 2021)
 
 ### FEATURES
 

README.md

@@ -1,6 +1,6 @@
 # Ystia Orchestrator
 
-[![Download](https://img.shields.io/badge/download-v4.2.0--milestone.1-blue)](https://github.com/ystia/yorc/releases/tag/v4.2.0-milestone.1) [![Build Status](https://github.com/ystia/yorc/actions/workflows/build.yml/badge.svg?branch=release/4.2)](https://github.com/ystia/yorc/actions) [![Documentation Status](https://readthedocs.org/projects/yorc/badge/?version=latest)](http://yorc.readthedocs.io/en/latest/?badge=latest) [![Go Report Card](https://goreportcard.com/badge/github.com/ystia/yorc)](https://goreportcard.com/report/github.com/ystia/yorc) [![license](https://img.shields.io/github/license/ystia/yorc.svg)](https://github.com/ystia/yorc/blob/develop/LICENSE) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square)](http://makeapullrequest.com) [![Docker Pulls](https://img.shields.io/docker/pulls/ystia/yorc.svg?style=flat)](https://hub.docker.com/r/ystia/yorc) [![Join the chat at https://gitter.im/ystia/yorc](https://badges.gitter.im/ystia/yorc.svg)](https://gitter.im/ystia/yorc?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Download](https://img.shields.io/badge/download-v4.2.0--milestone.1-blue)](https://github.com/ystia/yorc/releases/tag/v4.2.0) [![Build Status](https://github.com/ystia/yorc/actions/workflows/build.yml/badge.svg?branch=release/4.2)](https://github.com/ystia/yorc/actions) [![Documentation Status](https://readthedocs.org/projects/yorc/badge/?version=latest)](http://yorc.readthedocs.io/en/latest/?badge=latest) [![Go Report Card](https://goreportcard.com/badge/github.com/ystia/yorc)](https://goreportcard.com/report/github.com/ystia/yorc) [![license](https://img.shields.io/github/license/ystia/yorc.svg)](https://github.com/ystia/yorc/blob/develop/LICENSE) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square)](http://makeapullrequest.com) [![Docker Pulls](https://img.shields.io/docker/pulls/ystia/yorc.svg?style=flat)](https://hub.docker.com/r/ystia/yorc) [![Join the chat at https://gitter.im/ystia/yorc](https://badges.gitter.im/ystia/yorc.svg)](https://gitter.im/ystia/yorc?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 <p align="center">
   <img src="https://raw.githubusercontent.com/ystia/yorc/develop/doc/_static/logo/github-repository-open-graph-template.png" width="50%" height="50%" title="Yorc Logo">