doc: normalize C code block info strings

[DerekNonGeneric]

Prior to this commit, C fenced code blocks in Markdown files had
inconsistent info strings. This has been corrected to standardize on
the lowercase variant, which matches the others, is the typical file
extension for C files, and is the CSS class used by highlight.js
despite representing a minority of appearances in the doc/api/ dir.

Stats:

'C' => 181,
'c' => 3,

Refs: highlightjs/highlight.js#2577

Checklist

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

[DerekNonGeneric]

I've inspected the contents of the highlight.js bundle, and c is indeed one of the options. It's not listed on their documentation, but I've opened up a PR correcting that.

highlightjs/highlight.js#2577

[joshgoebel]

That's because it's new (as a language) though I'm pretty sure it's always existed as an alias of cpp.

[BridgeAR]

@nodejs/n-api @nodejs/documentation PTAL

[DerekNonGeneric]

@yyyc514, thanks for the tip! From what I gather, C and C++ use the same foundation grammar, so there's no real reason to make the distinction between the two since there's no observable difference. Is that right? I'm just a bit unclear if the info string for these should be cpp or further divided into c and h. A hint here would be greatly appreciated. :)

[addaleax]

I would keep C and C++ separate, they are different, not fully mutually compatible languages after all.

[joshgoebel]

From what I gather, C and C++ use the same foundation grammar, so there's no real reason to make the distinction between the two since there's no observable difference.

For now. But the intent is they diverge over time. So use the correct one. Future proof.

H is just an alias for C.

[mhdawson]

LGTM

[BridgeAR]

Landed in 84e4425