correct steps in ingress and service with coredns document

[xunpan]

There are 4 issues updated in the document

1. switch from minikube to kind
2. add RBAC for clusterrole external-dns
3. add labels to make kubefed controller works
4. update link to metallb

What this PR does / why we need it:
Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1217

Special notes for your reviewer:

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[xunpan]

/retest

[hectorj2f]

@xunpan isn't it possible to use minikube anymore ? should we exclude it as a list of supported environment ?

[xunpan]

@hectorj2f
For this document, I update it to kind because minikube is not our defaullt simulated multiple clusters environment anymore. A case on kind can be easily move to minikube on demand.

To me, I think we do not need to maintain minikube because currently kind works fine. I do not see any value to have multiple simulated environment maintained.

[hectorj2f]

@xunpan Perhaps we should ask if we want to maintain examples for minikube in the community channel.

/lgtm