[platform/ec/docs] - Update link on partnersite.
Update the location of the firmwaretestmanual.html link, which must have
moved on partnersite.
BRANCH=None
TEST=Visual inspection.
@@ -57,7 +57,7 @@ Another way of disabling hardware write protection is to remove the battery;
this method is mainly used during bringup.
Additional reference:
-https://www.google.com/chromeos/partner/fe/docs/cpfe/firmwaretestmanual.html#hardware-write-protect
+https://chromium.googlesource.com/chromiumos/docs/+/HEAD/write_protection.md
## Changing Hardware Write Protection
