qapi: Use explicit bulleted lists

qapi: Use explicit bulleted lists

A JSON block comment like this:
     Returns: nothing on success
              If @node is not a valid block device, DeviceNotFound
              If @name is not found, GenericError with an explanation

renders like this:

     Returns: nothing on success If node is not a valid block device,
     DeviceNotFound If name is not found, GenericError with an explanation

because whitespace is not significant.

Use an actual bulleted list, so that the formatting is correct.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200213175647.17628-14-peter.maydell@linaro.org>
Message-Id: <20200213175647.17628-15-peter.maydell@linaro.org>
Message-Id: <20200213175647.17628-16-peter.maydell@linaro.org>
[Three commits squashed into one]
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>