doc: normalize JavaScript code block info strings

[DerekNonGeneric]

Prior to this commit, JavaScript fenced code blocks in Markdown files
had inconsistent info strings. This has been corrected to standardize
on the one with the highest frequency in the doc/api/ dir.

Stats:

'js' => 1091,
'javascript' => 2,

Checklist

• documentation is changed or added
• commit message follows commit guidelines

[BridgeAR]

@DerekNonGeneric since you open multiple PRs at the moment: the subsystem for the commit message should be doc, otherwise we'll have to change it during landing.

[DerekNonGeneric]

I would just like to point out that the info string should probably be javascript and that js is just an alias for javascript. I don't anticipate this being a problem seeing as how GitHub and highlight.js treat them identically. Notably, info strings are not determined by a language's file extension(s) and since we are going to be using markdown for Markdown, it might be nice to go w/ javascript for JavaScript to continue in this trend of using the lowercase form of the entire name of the language.

Refs:

• https://github.com/highlightjs/highlight.js/blob/f30dbf774a1cb4c9644b6e97b0b853812e434038/src/languages/javascript.js#L99
• https://github.com/libgit2/libgit2/blob/27cb4e0ec193aa5430d1a32fd90b5dc2d86f5fe1/src/userdiff.h#L195

/cc @yyyc514

[joshgoebel]

If you want the canonical name it’s javascript. But the “js” alias isn’t going anywhere so up to you.

[BridgeAR]

Landed in 4a8f6b6