OpenStack uses reStructuredText to document their REST API.

Example:

• https://docs.openstack.org/api-ref/database/?expanded=id30-detail,create-datastore-version-detail
• Source: https://opendev.org/openstack/trove/src/branch/master/api-ref/source
• Source: https://opendev.org/openstack/trove/src/branch/master/api-ref/source/datastore-versions.inc

They use rST with shared parameter definitions in a parameters.yaml file, and have custom directives like .. rest_method:: and .. rest_parameters::