doc: add support doc

[andyzhangx]

What type of PR is this? /kind documentation

What this PR does / why we need it: doc: add support doc

Which issue(s) this PR fixes:

Fixes #

Requirements:

• [ ] uses conventional commit messages
• [ ] includes documentation
• [ ] adds unit tests
• [ ] tested upgrade from previous version

Special notes for your reviewer:

Release note:

none

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-csi/csi-driver-nfs/blob/master/OWNERS)~~ [andyzhangx] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[coveralls]

Pull Request Test Coverage Report for Build 10630648863

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 78.659%

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Totals
Change from base Build 10613539965:	0.0%
Covered Lines:	903
Relevant Lines:	1148

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💛 - Coveralls