Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

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

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

mdoc: remove superfluous paragraph macro.

Import work done under project/nand (@235533) into head.

The NAND Flash environment consists of several distinct components:
- NAND framework (drivers harness for NAND controllers and NAND chips)
- NAND simulator (NANDsim)
- NAND file system (NAND FS)
- Companion tools and utilities
- Documentation (manual pages)

This work is still experimental. Please use with caution.

Obtained from: Semihalf
Supported by: FreeBSD Foundation, Juniper Networks