Update Style Guide for Version handling

Issue

The docs include version information about when functionality was added. While this information is useful, maintaining that information over time adds technical debt.

Much of this version information is readily available in other places, including:

• The issue where the work occurred.
• Release posts.

Right now, our guidance states that older information is a "candidate for removal if necessary for clearer or cleaner documentation." We want this guidance to be more decisive.

Proposal

Per the Handbook, the Support team supports the current major version and the two previous major versions. Our product documentation should match this policy.

This means that:

• We should remove any information that is older than the past two major versions. This means removing information from 10.x and earlier.
• We shouldn't mention tiers in version statements, or announce tier changes as a versioned item. We have product badges at the header level, and they should be a SSOT for this sort of information.

(Since we're talking about versions and how we should handle their information, note that there's also some refinement with the EOL and deprecation info, with guidance on how and when to remove deprecated information from the documentation.)

These updates to the Style Guide describe these changes, and implementation details around them. I realize these changes would have us go and remove information from the docs, which I envision would happen over time and as we're working on other items (similar to how we handled notes removal after the initial removal effort occurred).

I appreciate any comments or suggestions, but as for all process improvements, I want to get an MVC in place and working sooner than later, so that we can iterate and evaluate things as they go. I'll at least leave this open long enough to allow for everyone on the team to have an opportunity to comment. Thanks!

Mentioning @gl-docsteam for review of this style guide update for version handling.

Related issues

!48145 (closed)

Author's checklist (required)

• Follow the Documentation Guidelines and Style Guide.
• If you have Developer permissions or higher:
  • Ensure that the product tier badge is added to doc's h1.
  • Apply the documentation label, plus:
    • The corresponding DevOps stage and group labels, if applicable.
    • development guidelines when changing docs under doc/development/*, CONTRIBUTING.md, or README.md.
    • development guidelines and Documentation guidelines when changing docs under development/documentation/*.
    • development guidelines and Description templates (.gitlab/*) when creating/updating issue and MR description templates.
  • Assign the designated Technical Writer.

Do not add the feature, frontend, backend, ~"bug", or database labels if you are only updating documentation. These labels will cause the MR to be added to code verification QA issues.

When applicable:

• Update the permissions table.
• Link docs to and from the higher-level index page, plus other related docs where helpful.
• Add the product tier badge accordingly.
• Add GitLab's version history note(s).
• Add/update the feature flag section.

Review checklist

All reviewers can help ensure accuracy, clarity, completeness, and adherence to the Documentation Guidelines and Style Guide.

1. Primary Reviewer

• Review by a code reviewer or other selected colleague to confirm accuracy, clarity, and completeness. This can be skipped for minor fixes without substantive content changes.

2. Technical Writer

• Technical writer review. If not requested for this MR, must be scheduled post-merge. To request for this MR, assign the writer listed for the applicable DevOps stage.
  • Ensure docs metadata are present and up-to-date.
  • Ensure Technical Writing and documentation are added.
  • Add the corresponding docs:: scoped label.
  • If working on UI text, add the corresponding UI Text scoped label.
  • Add twdoing when starting work on the MR.
  • Add twfinished if Technical Writing team work on the MR is complete but it remains open.

For more information about labels, see Technical Writing workflows - Labels.

For suggestions that you are confident don't need to be reviewed, change them locally and push a commit directly to save others from unneeded reviews. For example:

• Clear typos, like this is a typpo.
• Minor issues, like single quotes instead of double quotes, Oxford commas, and periods.

For more information, see our documentation on Merging a merge request.

3. Maintainer

1. Review by assigned maintainer, who can always request/require the above reviews. Maintainer's review can occur before or after a technical writer review.
2. Ensure a release milestone is set.
3. If there has not been a technical writer review, create an issue for one using the Doc Review template.