doc: improve README.md

Make text more concise and remove some use of passive voice.

PR-URL: https://github.com/nodejs/node/pull/23705


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matheus Marchini <mat@mmarchini.me>
Reviewed-By: Refael Ackermann <refack@gmail.com>