🐛 Fix cert manager repo and add troubleshooting guide

[killianmuldoon]

Signed-off-by: killianmuldoon kmuldoon@vmware.com

Update cert manger URL and add a troubleshooting section for older versions of CAPI. This PR fixes an issue where a change in the location of the cert manager repo prevented clusterctl init from working.

Fixes: #6051

[k8s-ci-robot]

@killianmuldoon: 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-0-4	2eaa478	link	false	/test pull-cluster-api-apidiff-release-0-4

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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. I understand the commands that are listed here.

[fabriziopandini]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabriziopandini

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 [fabriziopandini]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment