docs/fingerprint: Document flash error on icetower
docs/fingerprint: Document flash error on icetower

Flashing Icetower with flash_ec and servo micro does not work at the
moment - see timeout error in b/177331210.

Document the known issue and provide link to workaround using J-Link.

BRANCH=none
BUG=b:177331210
TEST=view in gitiles

Signed-off-by: Andrea Grandi <f017805e76e0e7a74072a3bac1b6e29e65eedeab@google.com>
Change-Id: I1d4895f1723b55ca07a8717f984afc696865e8d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3502650
Reviewed-by: Tom Hughes <fc5c12f30a5ed2baa0581f44ee14ad1eb7b20d83@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec