Add Jenkins builds to the README
[![forthebadge made-with-java](https://ForTheBadge.com/images/badges/made-with-java.svg)](https://java.com/)
[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
+[![Build Status](https://ci.nukkitx.com/job/GeyserMC/job/Geyser-Fabric/job/java-1.16/badge/icon)](https://ci.nukkitx.com/job/GeyserMC/job/Geyser-Fabric/job/java-1.16/)
[![Discord](https://img.shields.io/discord/613163671870242838.svg?color=%237289da&label=discord)](http://discord.geysermc.org/)
Geyser-Fabric is Geyser specifically built for the Fabric modding platform.
