add log space clarification
add log space clarification

jasonscut/warp-ctc,baidu-research/warp-ctc,baidu-research/warp-ctc,jaredcasper/warp-ctc,jaredcasper/warp-ctc,baidu-research/warp-ctc,jasonscut/warp-ctc,jaredcasper/warp-ctc