Fix Matrix badge and replace the latest release notice with a badge (#749)

* The shiels.io page seems to generate wrong links (sorry for that!) I reported it to the shields.io project to fix this ASAP.
* Replaced the "latest release" notice information with a badge which automatically fetches the latest "Release" which means no one has to manually edit the readme each time a new release was introduced.

README.md

@@ -1,11 +1,11 @@
 # ![dnscrypt-proxy 2](https://raw.github.com/jedisct1/dnscrypt-proxy/master/logo.png?3)
 
-[![Build Status](https://travis-ci.org/jedisct1/dnscrypt-proxy.svg?branch=master)](https://travis-ci.org/jedisct1/dnscrypt-proxy?branch=master) ![Matrix](https://img.shields.io/matrix/dnscrypt-proxy:matrix.org.svg?label=DNSCrypt-Proxy%20Matrix%20Chat&server_fqdn=matrix.org&style=popout)
+[![DNSCrypt-Proxy Release](https://img.shields.io/github/release/jedisct1/dnscrypt-proxy.svg?label=Latest%20Release&style=popout)](https://github.com/jedisct1/dnscrypt-proxy/releases/latest)  [![Build Status](https://travis-ci.org/jedisct1/dnscrypt-proxy.svg?branch=master)](https://travis-ci.org/jedisct1/dnscrypt-proxy?branch=master) [![#dnscrypt-proxy:matrix.org](https://img.shields.io/matrix/dnscrypt-proxy:matrix.org.svg?label=DNSCrypt-Proxy%20Matrix%20Chat&server_fqdn=matrix.org&style=popout)](https://matrix.to/#/#dnscrypt-proxy:matrix.org)
+
+## Overview
 
 A flexible DNS proxy, with support for modern encrypted DNS protocols such as [DNSCrypt v2](https://dnscrypt.info/protocol) and [DNS-over-HTTPS](https://www.rfc-editor.org/rfc/rfc8484.txt).
 
-## [dnscrypt-proxy 2.0.19 final is available for download!](https://github.com/jedisct1/dnscrypt-proxy/releases/latest)
-
 * [dnscrypt-proxy documentation](https://dnscrypt.info/doc) – This project's documentation (Wiki)
 * [DNSCrypt project home page](https://dnscrypt.info/)
 * [DNS-over-HTTPS and DNSCrypt resolvers](https://dnscrypt.info/public-servers)