doc: use serial comma in fs docs

[tniessen]

node/doc/README.md

Line 21 in 5e9274a

*[Use serial commas][].

Refs: #11321
Refs: #17384

[github-actions]

Fast-track has been requested by @tniessen. Please 👍 to approve.

[LiviaMedeiros]

Nits, feel free to ignore or leave for later:

node/doc/api/fs.md

Line 1562 in 4d5bbc7

`data` can be a string, a buffer, an{AsyncIterable} or{Iterable} object.

node/doc/api/fs.md

Line 1687 in 4d5bbc7

`fs.open()`, `fs.readFile()` or `fs.writeFile()`. Doing

node/doc/api/fs.md

Line 2412 in 4d5bbc7

`fs.open()`, `fs.readFile()` or `fs.writeFile()` is not recommended. Doing

node/doc/api/fs.md

Line 3876 in 4d5bbc7

`fs.open()`, `fs.readFile()` or `fs.writeFile()` is not recommended.

node/doc/api/fs.md

Line 7524 in 4d5bbc7

through `fs.open()` or `fs.writeFile()` or `fsPromises.open()`) will fail with

Out of curiosity, maybe comma should be used in those as well, since any TypedArray is equivalent of Int8Array, ..., or Float64Array:

node/doc/api/fs.md

Lines 4395 to 4396 in 4d5bbc7

	description: The `buffer` parameter can now be any `TypedArray` or a
	`DataView`.

[tniessen]

Thanks @LiviaMedeiros, I missed those! Force-pushed, the actual diff since the first commit is 1238886. PTAL.

[tniessen]

Thanks for catching that @LiviaMedeiros! Force-pushed again, the actual diff is cf0fb14.

[nodejs-github-bot]

Landed in d1d30d7