CI: make test-gen-api-docs is failing quite often

[aLekSer]

What happened:
Multiple Builds were failed:
https://console.cloud.google.com/cloud-build/builds/74de68e2-12de-4ab5-b8e1-ed0c4b6f47b0;step=17?project=agones-images
in this Pull Request for instance: #1685

< <h3 id="multicluster.agones.dev/v1.GameServerAllocationPolicy">GameServerAllocationPolicy
< <h3 id="multicluster.agones.dev/v1.GameServerAllocationPolicySpec">GameServerAllocationPolicySpec
3260a3266
> <p>
5211c5217
< This field is beta-level and is enabled by default, could be disabled by the &ldquo;ContainerPortAllocation&rdquo; feature.</p>
---
> This field is alpha-level and is only honored by servers that enable the &ldquo;ContainerPortAllocation&rdquo; feature.</p>
5517,5518c5523,5524
< {{% feature expiryVersion="1.8.0" %}}
< {{% feature publishVersion="1.8.0" %}}
---
> {{% feature expiryVersion="1.7.0" %}}
> {{% feature publishVersion="1.7.0" %}}
includes/website.mk:98: recipe for target 'test-gen-api-docs' failed

What you expected to happen:
No fails on make test-gen-api-docs

How to reproduce it (as minimally and precisely as possible):
Could not reproduce as of know.

Anything else we need to know?:

Environment:

• Agones version: master (1.8.0-dev)
• Kubernetes version (use kubectl version): n/a
• Cloud provider or hardware configuration: CloudBuilds
• Install method (yaml/helm):
• Troubleshooting guide log(s):
• Others:

[aLekSer]

I was able to reproduce this locally on MacOS 10.14.4, Docker Desktop 2.3.0.3.

Both generated files are of the same size. So the root cause is that @ahmetb gen-crd-api-reference-docs utility could not guarantee the order of objects of the same level of nesting I suppose. Thus this should not cause the logical difference between two files.
There is no diff between two versions:

diff <(sort ./agones_crd_api_reference.html) <(sort ./agones_crd_api_reference2.html) | wc -l
0
diff ././agones_crd_api_reference.html ././agones_crd_api_reference2.html
2818

You can compare this https://gist.github.com/aLekSer/13d6333c7e821e73919c384626d7bd2b to master version https://github.com/googleforgames/agones/blob/c97864fd8815212682c546facb900b3931e35f21/site/content/en/docs/Reference/agones_crd_api_reference.html

Meld diff tool output: