fix wrong directory in manual doc, hack.txt.
fix wrong directory in manual doc, hack.txt.

BUG=None
TEST=No source code changes, only doc change

Change-Id: I51cf401e34ef7f9f5f8b5546393cd7b4bf560b83
Reviewed-on: https://gerrit.chromium.org/gerrit/47987
Commit-Queue: Robert Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>
Reviewed-by: Robert Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>
Tested-by: Robert Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>

hernad/libapps,hernad/libapps,hernad/libapps,hernad/libapps