Update README.md

Author: codingchili

README.md

@@ -20,12 +20,15 @@ Perform the following steps to create an installable zip:
 
 - NodeJS 6.9.2+
 - NPM
-- MS Build tools
+- MS Build tools / Unix build tools
 - Python 2.7
 
 To compile the binary module argon2-ffi build tools are requried, install with
 ```
-npm install --global --production windows-build-tools
+windows: 
+  npm install --global --production windows-build-tools
+unix:    
+  sudo apt-get install -y build-essential
 ```
 This installs MS build tools and python 2.7 and is required for node-gyp to work.
 
@@ -64,4 +67,4 @@ No plans on implementing this for now.
 - running npm --install with --arch=ia32 breaks mocha but works with Kibana.
 - running npm --install without --arch=ia32 works with mocha but not Kibana.
 
-We are not happy about this.
+We are not happy about this.