Switch logging service from log.tailscale.io to log.tailscale.com (#14398)

Updates tailscale/corp#23617

Signed-off-by: Joe Tsai <joetsai@digital-static.net>

logtail/example/logreprocess/demo.sh

@@ -13,7 +13,7 @@
 #
 # Then generate a LOGTAIL_API_KEY and two test collections by visiting:
 #
-#        https://log.tailscale.io
+#        https://log.tailscale.com
 #
 # Then set the three variables below.
 trap 'rv=$?; [ "$rv" = 0 ] || echo "-- exiting with code $rv"; exit $rv' EXIT