Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
update ipvs readme file
**What this PR does / why we need it**:
Since some iptables rules that ipvs proxier installed have changed, we need update ipvs readme file.
**Special notes for your reviewer**:
1. fix some error, like nodePort realization.
2. Update iptables rules.
3. Add externalIP
4. Add ipset sets introduction
**Release note**:
```release-note
NONE
```
There's a disconnect between 12d4eac038
and the earlier a6af827898. One says
KUBEPROXY_MODE and another says KUBE_PROXY_MODE. Let's just pick one.
Currently we fail with the following error:
hack/local-up-cluster.sh: line 808: KUBEPROXY_MODE: unbound variable
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Update IPVS README
**What this PR does / why we need it**:
People complained that they feel confused about how to use IPVS-based kube-proxy correctly, probably we may need to provide them a better README.
**Which issue(s) this PR fixes**:
xref: #56319
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```