Pull Documentation updates from Jon Corbet:
 "A bit busier this time around.

  The most interesting thing (IMO) this time around is some beginning
  infrastructural work to allow documents to be written using
  restructured text.  Maybe someday, in a galaxy far far away, we'll be
  able to eliminate the DocBook dependency and have a much better
  integrated set of kernel docs.  Someday.

  Beyond that, there's a new document on security hardening from Kees,
  the movement of some sample code over to samples/, a number of
  improvements to the serial docs from Geert, and the usual collection
  of corrections, typo fixes, etc"

* tag 'docs-for-linus' of git://git.lwn.net/linux: (55 commits)
  doc: self-protection: provide initial details
  serial: doc: Use port->state instead of info
  serial: doc: Always refer to tty_port->mutex
  Documentation: vm: Spelling s/paltform/platform/g
  Documentation/memcg: update kmem limit doc as codes behavior
  docproc: print a comment about autogeneration for rst output
  docproc: add support for reStructuredText format via --rst option
  docproc: abstract terminating lines at first space
  docproc: abstract docproc directive detection
  docproc: reduce unnecessary indentation
  docproc: add variables for subcommand and filename
  kernel-doc: use rst C domain directives and references for types
  kernel-doc: produce RestructuredText output
  kernel-doc: rewrite usage description, remove duplicated comments
  Doc: correct the location of sysrq.c
  Documentation: fix common spelling mistakes
  samples: v4l: from Documentation to samples directory
  samples: connector: from Documentation to samples directory
  Documentation: xillybus: fix spelling mistake
  Documentation: x86: fix spelling mistakes
  ...