README.md: Use proper headline formatting.
README.md: Use proper headline formatting.

Signed-off-by: Gurucharan Shetty <a1872e333d0e52644f6125da2276530f7ebe5e77@ovn.org>
Acked-by: 6917553b3b6b807081627821e2c4fcf1212a4475@ovn.org

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