Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix typos, spelling, formatting and mdoc mistakes found by Nobuyuki while
translating these manual pages. Minor corrections by me.

Submitted by: Nobuyuki Koganemaru <n-kogane@syd.odn.ne.jp>

o Sort Xrs.

Change reference from mount(2) to nmount(2), since mount(8) uses
nmount to mount an mqueufs filesystem.

Revise markup.

Fix markup.

Add document about mqueuefs.