eck_version, eck_release_branch and eck_helm_minimum_version subs

[eedugon]

ECK substitutions applied, using current asciidoc (2.16) substitutions as reference.

eck_helm_minimum_version is an improvement as the minimum supported helm version appeared hardcoded in multiple docs.

Note that in the current asciidoc we also have a substitution like eck_github: https://github.com/elastic/cloud-on-k8s not used here. If that's considered useful I can apply it everywhere also.

Pending to determine if we should add also eck_crd_version the same way it was used in original asciidoc files.

[barkbay]

IIUC these fields are going to be maintained by the ECK team? If it is the case we should update our release issue template: https://github.com/elastic/k8s-dev/blob/main/.github/ISSUE_TEMPLATE/release-issue-template.md

[eedugon]

@barkbay , yes, you will be in charge of maintaining the V3-docs after 9.0 / 3.0.0 releases.

Now the majority of ECK docs are in docs-content, while release notes, known issues, breaking changes, etc are kept in the cloud-on-k8s repo.

That means that for the moment the substitution variables need to be maintained in both places. Although I've heard from @bmorelli25 that we have plans to improve this and provide a single point for the global variables definition and maintenance.

Do you want me to write a PR or an issue to update your k8s-dev releases template? Although I'm not familiar with your overall releasing procedure.

[barkbay]

Do you want me to write a PR or an issue to update your k8s-dev releases template? Although I'm not familiar with your overall releasing procedure.

I update the last step in the release process to not forget to update this template. See the last step in the "Post release" section here.

[eedugon]

perfect! In that template I still see mentions to the old asciidoc files and not to the new markdown docs.
Remember that now we don't use the asciidoc system anymore and some of the docs that appear in the template doesn't exist in main.

[kvalliyurnatt]

Thanks @eedugon and @barkbay I will make sure the references to asciidoc are updated and also will add the other changes to the releasee template

[eedugon]

perfect @kvalliyurnatt, thanks! If you need any help or information from my side about new docs system or when to touch the old asciidoc files (available only for 2.x branches), ping me in private!

[shainaraskas]

variables lgtm.