Fix outdated "60 fps in iOS" sentence.

[sebastiancarlos]

Description

At "Performance Overview", there is a focus on aiming at 60 fps which could be outdated. Particularly, "Performance Overview > What you need to know about frames" says that "iOS devices display 60 frames per second".

Currently, Ssome iOS devices and many Android devices offer displays with high refresh rates, including 120Hz. Additionally, some Android devices also offer 90Hz displays.

The phrasing could be changed to suggest aiming at "at least 60fps"

Documentation version

next, and likely earlier