Documentation for Deploy Tokens instance API endpoint

This is a post-merge review issue for the documentation introduced in !25066 (merged)

References

Merged MR that introduced documentation requiring review:

!25066 (merged)

Related issue(s):

#21811 (closed)

Further Details

A new Grape API endpoint that returns all deploy tokens at an instance level. Admin permission is required to make this request. This introduces a new resource to the API (deploy tokens)

curl gitlab.example.com/api/v4/deploy_tokens?access_token=<admin_access_token>

Response

[
    {
        "id": 1,
        "name": "Foo",
        "username": "gitlab+deploy-token-1",
        "expires_at": "2020-02-14T00:00:00.000Z",
        "token": "jMRvtCNxrn3crTEGukpZ",
        "scopes": [
            "read_repository",
            "read_registry"
        ]
    }
]