Update README

Add prerequisite for Node.js versions supported.

README.md

@@ -8,6 +8,8 @@ Node.js bindings to Xiph's [RNNoise denoising C library](https://github.com/xiph
 
 **Announcement**
 
+Jan 2021:
+
 >
 > I have been working on a new project that will bring this technology to you. A sneak peak at the new deep noise suppression and source separation model and audio output quality:
 >
@@ -17,6 +19,8 @@ Node.js bindings to Xiph's [RNNoise denoising C library](https://github.com/xiph
 
 ## Install
 
+Node.js versions supported: 8, 10
+
 [![NPM](https://nodei.co/npm/rnnoise.png?compact=true)](https://nodei.co/npm/rnnoise/)
 
 ## Use