Move the best practice doc to markdown

This document is pretty out of date and covers a lot of ground that is
not generally useful outside a chrome os context.  However, it is a
start and encodes a lot of the knowledge we've gained over the years
using autotest.

BUG=b:26912592
TEST=None

Change-Id: I375fca5b6a806f323f7c60a27e7d2c6ae6a3d341
Reviewed-on: https://chromium-review.googlesource.com/325349
Commit-Ready: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
1 file changed