Remove VERSION file in che-docs; keep antora-playbook.yml up to date instead

[themr0c]

The content of the PR is always false. The master branch contains the documentation for the released version of Che but the bot is always trying to update the file to the next version. Very confusing.

Example erroneous PR: eclipse-che/che-docs#1806

I am not aware of any process in che-docs using the VERSION file. We should probably remove it completely to remove a source of confusion.

The only relevant place to define the Che version should be in https://github.com/eclipse/che-docs/blob/master/antora-playbook.yml

    prod-prev-ver-major: 6
    prod-prev-ver: 7.22
    prod-ver-major: 7
    prod-ver: 7.23
    prod-ver-patch: 7.23.2

If we want to keep an automated process, please make sure it is setting the released version of Che in antora-playbook.yml (as well as the previous version).

[nickboldt]

So we'd want to update this bit of code:

https://github.com/eclipse/che-docs/pull/1802/files#diff-be36842270d47fd0f7dd297abbdf5c5ef7916efe78fd4617f5ca6a5fdcba421cR18-R19

to update antora-playbook.yml instead of VERSION file.

I suspect that fixing this issue will also mean that pages like https://www.eclipse.org/che/docs/che-7/end-user-guide/creating-and-configuring-a-new-workspace/ will be up to date (and thus show 7.25 instead of 7.23)

[yhontyk]

Jira docs issue https://issues.redhat.com/browse/RHDEVDOCS-2538

[nickboldt]

PR for making playbook current w/ every weekly release: eclipse-che/che-docs#1823

Then PR to trigger the above from a che-operator release (push to master branch): eclipse-che/che-operator#657

Note that with these changes, we'll want to disable the bit of the che-release cico script that triggers changes to che-docs:

https://github.com/eclipse/che-release/pull/24/files#diff-00f10a3f2d34c8611e384da8b9b2b9283abcb69a4c3fa242e5a5ac5ba782abcfL113-R124