Fix GN docs for 'gn help deps' and update reference.md.

The help for 'deps' was at best misleading, so we've removed
the misleading parts.

Also, the reference markdown was out of date, so I've regenerated it.

R=brettw@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1359113003

Cr-Original-Commit-Position: refs/heads/master@{#350269}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: aedcc8a8ea65cb485bafbb4452d29c03e404cd5f
2 files changed
tree: 8ab35cd94b63a969216a538adcc7fb8dc0ec7c58
  1. tools/