Specifying the documentation at the place where the enumeration values are defined works:

    /** @brief A foo enumeration. */
    enum class Foo
    {
        A, /**< @brief The first value. */
        B, /**< @brief The second value. */
    };

Documenting the enumeration type outside the definition works:

    /** @enum Foo
      * @brief A foo enumeration.
      */

However, documenting the values outside the definition does not:

    /** @var Foo A
      * @brief The first value.
      */

    /** @var Foo B
      * @brief The second value.
      */

Nor does qualifying the values:

    /** @var Foo Foo::A
      * @brief The first value.
      */

    /** @var Foo Foo::B
      * @brief The second value.
      */

These all work for C++98/03 enumeration values.