Document ROXIE redundancy config options.

// Generate the slave channels
        unsigned numDataCopies = topology->getPropInt("@numDataCopies", 1);
        if (!numDataCopies)
            throw MakeStringException(MSGAUD_operator, ROXIE_INVALID_TOPOLOGY, "Invalid topology file - numDataCopies should be > 0");
        unsigned channelsPerNode = topology->getPropInt("@channelsPerNode", 1);
        unsigned numNodes = getNumNodes();
        const char *slaveConfig = topology->queryProp("@slaveConfig");
        if (!slaveConfig)
            slaveConfig = "simple";
        if (strnicmp(slaveConfig, "cyclic", 6) == 0)
        {
            numChannels = numNodes;
            unsigned cyclicOffset = topology->getPropInt("@cyclicOffset", 1);
            for (unsigned i=0; i<numNodes; i++)
            {
                // Note this code is a little confusing - easy to get the cyclic offset backwards
                // cyclic offset means node n+offset has copy 2 for channel n, so node n has copy 2 for channel n-offset
                int channel = (int)i+1;
                for (unsigned copy=0; copy<numDataCopies; copy++)
                {
                    if (channel < 1)
                        channel = channel + numNodes;
                    addChannel(i, channel, copy);
                    channel -= cyclicOffset;
                }
            }
        }
        else if (strnicmp(slaveConfig, "overloaded", 10) == 0)
        {
            if (!channelsPerNode)
                throw MakeStringException(MSGAUD_operator, ROXIE_INVALID_TOPOLOGY, "Invalid topology file - channelsPerNode should be > 0");
            numChannels = numNodes * channelsPerNode;
            for (unsigned i=0; i<numNodes; i++)
            {
                int channel = (int)(i+1);
                for (unsigned copy=0; copy<channelsPerNode; copy++)
                {
                    addChannel(i, channel, copy);
                    channel += numNodes;
                }
            }
        }
        else    // 'Full redundancy' or 'simple' mode
        {
            if (numNodes % numDataCopies)
                throw MakeStringException(MSGAUD_operator, ROXIE_INVALID_TOPOLOGY, "Invalid topology file - numChannels not an integer");
            numChannels = numNodes / numDataCopies;
            int channel = 1;
            for (unsigned i=0; i<numNodes; i++)
            {
                addChannel(i, channel, 0);
                channel++;
                if ((unsigned)channel > numChannels)
                    channel = 1;
            }
        }