Master md files are out of date. Point to main branch in case someone
lands in master branch from an old link.
BUG=b:180952272,b:180921286
BRANCH=None
TEST=Preview changes with gerrit
Exempt-From-Owner-Approval: fixing docs
Change-Id: I6583b6c7fc21248eb49a6cd71e077fbdb5de2435
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2727846
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
Reviewed-by: Rob Barnes <robbarnes@google.com>
Auto-Submit: Sean Abraham <seanabraham@chromium.org>
Tested-by: Sean Abraham <seanabraham@chromium.org>