Add build status badge to README (#596)

Author: Khalian

README.md

@@ -1,5 +1,7 @@
 # Neural Amp Modeler Plug-in
 
+[![Build](https://github.com/sdatkinson/NeuralAmpModelerPlugin/actions/workflows/build-native.yml/badge.svg)](https://github.com/sdatkinson/NeuralAmpModelerPlugin/actions/workflows/build-native.yml)
+
 A VST3/AudioUnit plug-in\* for [Neural Amp Modeler](https://github.com/sdatkinson/neural-amp-modeler), built with [iPlug2](https://iplug2.github.io).
 
 - https://www.youtube.com/user/RunawayThumbtack