Fix broken links in https://metal3.io/blog/2019/06/25/Metal3.html

[tuminoid]

Here, Github links need updating to current location, files themselves should still exist. DZone links are archived, so they work but require login. 410 from dzone.com is handled in another issue, needs link checker config.

/help
/good-first-issue
/triage accepted

Errors in https://metal3.io/blog/2019/06/25/Metal3.html

• [404] https://github.com/kubernetes-sigs/cluster-api/blob/master/pkg/apis/cluster/v1alpha1/machineset_types.go | Failed: Network error: Not Found
• [410] https://dzone.com/articles/introducing-the-kubernetes-cluster-api-project-2 | Failed: Network error: Gone
• [404] https://github.com/openshift/cluster-api/tree/master/pkg/controller/machine | Failed: Network error: Not Found

[metal3-io-bot]

@tuminoid:
This request has been marked as suitable for new contributors.

Please ensure the request meets the requirements listed here.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-good-first-issue command.

In response to this:

Here, Github links need updating to current location, files themselves should still exist. DZone links are archived, so they work but require login. 410 from dzone.com is handled in another issue, needs link checker config.

/help
/good-first-issue
/triage accepted

Errors in https://metal3.io/blog/2019/06/25/Metal3.html

• [404] https://github.com/kubernetes-sigs/cluster-api/blob/master/pkg/apis/cluster/v1alpha1/machineset_types.go | Failed: Network error: Not Found
• [410] https://dzone.com/articles/introducing-the-kubernetes-cluster-api-project-2 | Failed: Network error: Gone
• [404] https://github.com/openshift/cluster-api/tree/master/pkg/controller/machine | Failed: Network error: Not Found

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[tuminoid]

#527 created for Dzone issue.