Minor fixups to authoring.md.
Minor fixups to authoring.md.

Mostly typo fixes and rewording for clarity.

Also update the link for the NDK to point to the hotfix for r14 so we
don't get an influx of obsolete bugs reports :)

jomof/cdep-work,jomof/cdep-work,google/cdep,jomof/cdep-work,google/cdep,jomof/cdep-work,google/cdep,google/cdep