Update multiroom.md
This change fix a little typo in the world "form" which should be "from" on the "Airplay" paragraph
Originally, Airplay wasn't designed for multiroom applications. Apple now used Airplay 2
(there are no open source implementations of this!) for multiroom audio.
However, even the "normal" Airplay can be used to stream to multiple endpoints. The bad news:
-this doesn't work from your iPhone or iPad, but only form iTunes.
+this doesn't work from your iPhone or iPad, but only from iTunes.
## LMS / squeezelite
