doc: adds NO_COLOR to assert doc page

Co-Authored-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/30483
Refs: https://github.com/nodejs/node/issues/30484


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>