Pull documentation updates from Jonathan Corbet:
 "A few late-arriving docs updates that have no real reason to wait.

  There's a new "Co-Developed-by" tag described by Greg, and a build
  enhancement from Willy to generate docs warnings during a kernel build
  (but only when additional warnings have been requested in general)"

* tag 'docs-4.15-2' of git://git.lwn.net/linux:
  Add optional check for bad kernel-doc comments
  Documentation: fix profile= options in kernel-parameters.txt
  documentation/svga.txt: update outdated file
  kokr/memory-barriers.txt: Fix typo in paring example
  kokr/memory-barriers/txt: Replace uses of "transitive"
  Documentation/process: add Co-Developed-by: tag for patches with multiple authors