Fix wording on Mojo security docs.

TBR=dcheng

Bug: 789374
Change-Id: I68d41425e0cf376d1346546268fac60bd9a6dc3c
Reviewed-on: https://chromium-review.googlesource.com/807184
Reviewed-by: Chris Palmer <palmer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521452}
1 file changed