tools: fix broken link in icu notes

Link text and url were swapped around, this pr puts
the link text inside [] and the url inside ().

PR-URL: https://github.com/nodejs/node/pull/20030


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>