As noted in the review form
DM-15563, we should be ignoring any detail namespaces when running Doxygen, as that namespace indicates symbols that should not be considered part of the public API. This can be done by setting:
in doxygen configuration.
However, for this to work, we'd actually need to standardize on whether to use detail or details as the namespace name, and a quick look at afw indicates that we haven't even done that. This convention was invented by Boost, which uses detail and we should go with that.