🐛 Fix cert manager repo and add troubleshooting guide

[k8s-infra-cherrypick-robot]

This is an automated cherry-pick of #6050

/assign fabriziopandini

[k8s-ci-robot]

@k8s-infra-cherrypick-robot: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-apidiff-release-1-1	7efd2b9	link	false	/test pull-cluster-api-apidiff-release-1-1

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[killianmuldoon]

/lgtm

[fabriziopandini]

/lgtm
/approve
/cherry-pick release-1.0

[k8s-infra-cherrypick-robot]

@fabriziopandini: once the present PR merges, I will cherry-pick it on top of release-1.0 in a new PR and assign it to you.

In response to this:

/lgtm
/approve
/cherry-pick release-1.0

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.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabriziopandini

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• OWNERS [fabriziopandini]

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[k8s-infra-cherrypick-robot]

@fabriziopandini: #6052 failed to apply on top of branch "release-1.0":

Applying: Fix cert manager repo and add troubleshooting guide
.git/rebase-apply/patch:51: new blank line at EOF.
+
warning: 1 line adds whitespace errors.
Using index info to reconstruct a base tree...
M	docs/book/src/user/troubleshooting.md
Falling back to patching base and 3-way merge...
Auto-merging docs/book/src/user/troubleshooting.md
CONFLICT (content): Merge conflict in docs/book/src/user/troubleshooting.md
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Fix cert manager repo and add troubleshooting guide
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/lgtm
/approve
/cherry-pick release-1.0

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.