A single newline does not break a paragraph, so these four lines run together in a way that would be best described as 'godawful'.

It might be best to reformat to something like this:

    Supported grants:
    - :class:`oauthlib.oauth2.WebApplicationClient` (default): Authorization Code Grant
    - :class:`oauthlib.oauth2.MobileApplicationClient`: Implicit Grant
    - :class:`oauthlib.oauth2.LegacyApplicationClient`: Password Credentials Grant
    - :class:`oauthlib.oauth2.BackendApplicationClient`: Client Credentials Grant

The bulleted list will look better and be clearer.