Added the build instructions for installing Preact.

Author: maratbn

BUILD_INSTRUCTIONS

@@ -58,7 +58,14 @@
     ...
 
 
-(10) Bundle / transpile the JavaScript with Webpack for deployment:
+(10) Install the NPM modules for Preact:
+
+    $ npm install preact preact-compat
+
+    ...
+
+
+(11) Bundle / transpile the JavaScript with Webpack for deployment:
 
     $ ./node_modules/webpack/bin/webpack.js --config ./webpack.config.js