Add build status badge to README (#163)

Added build status badge to README.

Author: Khalian

README.md

@@ -1,4 +1,7 @@
 # NeuralAmpModelerCore
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+[![Build](https://github.com/sdatkinson/NeuralAmpModelerCore/actions/workflows/build.yml/badge.svg)](https://github.com/sdatkinson/NeuralAmpModelerCore/actions/workflows/build.yml)
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 Core C++ DSP library for NAM plugins.
 
 For an example how to use, see [NeuralAmpModelerPlugin](https://github.com/sdatkinson/NeuralAmpModelerPlugin).