README.md: Fix ip addresses in --rampout-ip-subnets.
README.md: Fix ip addresses in --rampout-ip-subnets.

according to the following parameter --rampout-ip-subnets,
the ip address should be 192.168.1.0/24 and 192.168.2.0/24.

Signed-off-by:  mozhuli <02999de21b4193b140454adc4b6c39d718023abb@gmail.com>

shettyg/ovn-kubernetes,shettyg/ovn-kubernetes,shettyg/ovn-kubernetes