chunking related faq update

[longwuyuan]

What this PR does / why we need it:

• NGINX upstream made some changes related to chunking http://hg.nginx.org/nginx/rev/2bf7792c262e
• This PR addes a new FAQ bullet related to this change and its impact on the ingress-nginx controller

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

• Fixes Document chunking related change in v1.10 #11164

How Has This Been Tested?

• In issue since controller 1.10.0 (chart 4.10.0): ingress rejects duplicate "Transfer-Encoding: chunked" and returns 502 #11162

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• [x ] I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.

/kind documentation
/area docs
/triage accepted
/priority important-longterm

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[Gacko]

Basically fine, but could you maybe keep the format of the other lines?

[k8s-ci-robot]

@longwuyuan: you cannot LGTM your own PR.

In response to this:

/lgtm

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[Gacko]

/cherry-pick release-1.10

[k8s-infra-cherrypick-robot]

@Gacko: once the present PR merges, I will cherry-pick it on top of release-1.10 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.10

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[strongjz]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: longwuyuan, strongjz

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Needs approval from an approver in each of these files:

• docs/OWNERS [longwuyuan,strongjz]

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[k8s-infra-cherrypick-robot]

@Gacko: new pull request created: #11205

In response to this:

/cherry-pick release-1.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.