Rendered here: https://docs.github.com/en/enterprise-server@latest/admin/release-notes
A content file exists in content/admin/release-notes.md. It has a special frontmatter property layout: release-notes and no Markdown content. The source of the release notes comes from YAML data.
The source data for the release notes lives in this directory (data/release-notes/enterprise-server).
The directories are named by GHES release number (with a hyphen instead of a period).
The YAML files in each directory are named by patch number. Some patch filenames may end with -rc<num>.yml, which means it's a release candidate. A release candidate file also requires release_candidate: true in the YAML data.
Release notes of deprecated GHES versions (see lib/enterprise-server-releases.js) are not removed from the site and will always be displayed alongside currently supported versions.
Note that patch files can be deprecated individually (i.e., hidden on the docs site) by an optional deprecated: true property.
The YAML data is processed and sorted by middleware/contextualizers/release-notes.js and added to the context object.
The context object data is rendered by components/release-notes.
The release notes page has a custom design with CSS in stylesheets/release-notes.scss.
The schema that validates the YAML data lives in tests/helpers/schemas/ghes-release-notes-schema.js. See the schema file to find out the required and optional properties.
The schema is exercised by a test in tests/linting/lint-files.js. The test will fail if the data does not pass validation.