Remove the stale CHANGELOG.md

Problem/Motivation

CHANGELOG.md has drifted out of use and nothing in the project references it. Its dated release list duplicates the release page and stops at 2.0.0-beta3 in June 2025, so the whole 3.x series is missing from it. The "Status" section describes the 8.x-1.x branch, which is no longer maintained, and the alpha, beta and release candidate checklists below it are a record of work finished years ago.

Release notes on the release nodes are where this information belongs for a Drupal project, and they are already the only place anyone actually reads it.

Proposed resolution

Delete the file.

One section has to be preserved somewhere first. Under the heading "3.1.0 (#3588828)" the file carries the upgrade note for the split of domain_config and domain_config_ui into language-free modules plus domain_config_language and domain_config_language_ui. Most of it describes architecture that the documentation site already covers in three languages, but one line does not appear anywhere else:

Custom code typehinting the moved classes, DomainLanguageConfigFactoryOverride and its interface, DomainLanguageConfigOverride, DomainConfigLanguageManager and DomainLanguageConfigCollectionNameTrait, needs its use statements changed from the Drupal\domain_config namespace to Drupal\domain_config_language.

That is an upgrade instruction rather than a description of the current design, so it belongs in the 3.1.0 release notes rather than on the documentation site, which describes the module as it is now. The split shipped in 3.1.0-alpha4, so it affects anyone coming from 3.0.x and nobody moving between 3.1.0 alphas.

Remaining tasks

Carry that paragraph into the 3.1.0 release notes before or when the file is removed, so the instruction is not lost with it.

Apply on 4.x and backport to 3.x.

User interface changes

None.

API changes

None.

Data model changes

None.

AI-Generated: Yes (Claude Code was used to help draft this issue summary. I reviewed it before posting; the finding came out of a release readiness review and there is no merge request on this issue yet.)