[R]: update the comments on fm.set.cached.
[R]: update the comments on fm.set.cached.

icoming/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashX,flashxio/FlashX