Update 10-javascript.md

11: before talking about node explain further what exactly it is
"Language website" is also a pretty awkward-sounding header.
never mind, you used it for the "Ruby" chapter, too.
but it made more sense then cos it was just a link.
here it's just confusing because you talk about nodejs.
idk.
"Website for the language" might be too long but for the point of clarity/parallelism you may consider changing all the "Language website" headers to that.