doc: edit (general) collaborator guide

Use consistent capitalization in Consensus Seeking section, replace some
_should_ usage with imperative, etc.

PR-URL: https://github.com/nodejs/node/pull/34712


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ricky Zhou <0x19951125@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>