Note that build/chunked folder is included to demonstrate using build.sh for running "sencha compile". You can immediately preview the behavior by running the index.html from there. Running build.sh will recompile the JS files in build/chunked.
You can run index.html in the root (aka dev mode) - does not demonstrate the technique. For a standard build run any of the following:
At this point you can run the actual built app from build/[production|package|testing]