Create pointer to new topic on main site
Destroyed Tutorial (markdown)
Created Tutorial (markdown)
Updated Tutorial (markdown)
The nodejs executable is called 'node', at least on my system (mac / homebrew)
typo: hello_world.js is in src not tests
rename node->nodejs for the command line
Re-add ../emcc and update text about switching directories
Update ../emcc to ./emcc in tutorial
Refer to the SDK for setting up guide.