Fix supported platforms of powerMonitor

Editor assessment

A one-line documentation correction whose subject is complete: the supported platforms of powerMonitor were listed incorrectly and are now fixed. The docs type matches, no scope is needed for a single API reference edit, and no body is required because the change is self-explanatory and carries no trade-offs. There are no footers, which is appropriate, and nothing pasted or extraneous appears. Hygiene is good, with imperative phrasing, no trailing period, and no ticket junk. The message does exactly what a small docs fix should: tell the reader precisely what was wrong in one glance.