doc: remove outdated timeout.unref content
resolve: https://github.com/nodejs/node/issues/42239
I checked the code in v0.9.1, there is indeed a new Timer
process:
https://github.com/nodejs/node/blob/e6ce259d2caf338fec991c2dd447de763ce99ab7/lib/timers.js#L254-L267
But this is not the case now.