Update outdated links to ProjectConfig proto.

Change-Id: I208be8bfb845218d88608a877405bd8b6c192066
Reviewed-on: https://chromium-review.googlesource.com/c/1287095Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600550}

infra/config/global/luci-scheduler-dev.cfg

@@ -2,7 +2,7 @@
 #
 # For schema of this file and documentation see ProjectConfig message in
 #
-# https://chromium.googlesource.com/infra/luci/luci-go/+/master/scheduler/appengine/messages/cron.proto
+# https://chromium.googlesource.com/infra/luci/luci-go/+/master/scheduler/appengine/messages/config.proto
 
 
 acl_sets {

infra/config/global/luci-scheduler.cfg

@@ -2,7 +2,7 @@
 #
 # For schema of this file and documentation see ProjectConfig message in
 #
-# https://chromium.googlesource.com/infra/luci/luci-go/+/master/scheduler/appengine/messages/cron.proto
+# https://chromium.googlesource.com/infra/luci/luci-go/+/master/scheduler/appengine/messages/config.proto
 
 
 acl_sets {