doc: remove superfluous filenaming convention

It is debatable whether "it is considered good style" in Node.js to use
hypens or underscores to separate words in file names. Node.js has
little to say about that. Remove that material as it is superfluous.

PR-URL: https://github.com/nodejs/node/pull/28089


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>