R1:4c314a733c1d

Clarifying the operating system choices.

Test Plan: looked at words, words looked good

Reviewers: O1 Blessed Committers, chris

Reviewed By: O1 Blessed Committers, chris

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Tags: #documentation

Differential Revision: https://we.phorge.it/D25427