bug(contrib/coreos): fix Docker bridge

The fix in 10ec0c50a was invalid, because this caused the choice
of 10.212.0.0 as the gateway. Instead, we start the addressing at
10.212.0.1.

Author: carmstrong

contrib/coreos/user-data

@@ -15,7 +15,7 @@ coreos:
       ExecStartPre=/bin/mount --make-rprivate /
       # Run docker but don't have docker automatically restart
       # containers. This is a job for systemd and unit files.
-      ExecStart=/usr/bin/docker -d -s=btrfs --bip=10.212.0.0/16 -r=false -H fd://
+      ExecStart=/usr/bin/docker -d -s=btrfs --bip=10.212.0.1/16 -r=false -H fd://
 
       [Install]
       WantedBy=multi-user.target