Clarify hello-world stub file comments
Clarify hello-world stub file comments

I removed 'only' because it doesn't seem to serve a purpose.
I switched SKELETON to stub because we don't need to shout, and we use the term stub file elsewhere
on the site.
Lastly, I changed the file name to match the actual file name in the exercise.

marcCanipel/xjavascript,cloudleo/xjavascript,exercism/xjavascript,exercism/xjavascript,cloudleo/xjavascript,marcCanipel/xjavascript