disk_layout: Add comment about updating fs_size

The current common layout has an intentionally lowered fs_size so that
we can catch rootfs bloat at build time. Add a comment explaining that
the fs_size is intentionally low and can be increased per board.

BUG=b:195316471
TEST=CQ

Change-Id: I914a79d16712090b957a30542f7432ce8809d96c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3072434
Tested-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Anthony Tran <anthonytran@google.com>
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
3 files changed