fixed fastcgi userguide

[longwuyuan]

What this PR does / why we need it:

• The FastCGI feature user0guise was ambiguous
• After recent updates on > Has anyone been able to configure nginx-ingress -> fpm ? Been unable to configure this #8207, this PR makes the feature and the test of the feature a little more clear

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 #8207

How Has This Been Tested?

• Tested locally on Kind

Checklist:

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

/triage accepted
/kind documentation
/area docs
/priority backlog

cc @tao12345666333 @strongjz @Gacko @rikatz Please review/approve

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[Gacko]

/triage accepted
/kind documentation
/priority backlog
/lgtm

[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

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-sigs/prow repository.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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:

• docs/OWNERS [Gacko,longwuyuan]

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[k8s-infra-cherrypick-robot]

@Gacko: new pull request created: #11455

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-sigs/prow repository.