optimize chart readme

[huiwq1990]

What this PR does / why we need it:

1. As upgrade CustomResourceDefinition in Transition from apiextensions.k8s.io/v1beta1 to apiextensions.k8s.io/v1 #1296 , kubefed only support 1.16+
2. controllermanager docker image split into controller image and webhook image

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 #

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[makkes]

/lgtm

Thanks a lot, @huiwq1990.

[irfanurrehman]

Thanks @huiwq1990
I might be missing something, but it appears like there are duplicates. Please check and let me know.

[irfanurrehman]

This seems like a repeat of line 107?

[huiwq1990]

yes, i have fix them.

[irfanurrehman]

Did you mean controllermanager.webhook.imagePullPolicy?

[huiwq1990]

@irfanurrehman I have recheck my pr, and fix them.

[makkes]

We should put all options in (alphabetic?) order but that can be done in a subsequent PR.

/lgtm

[huiwq1990]

I prefer organize them by kubefed’s module(webhook,controller). User know how to config them at first glance.

[irfanurrehman]

Thanks @huiwq1990
/approve

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: huiwq1990, irfanurrehman, makkes

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