Added a document for flowlog (#142, #156).
Added a document for flowlog (#142, #156).

akirakw/asakusafw,asakusafw/asakusafw,asakusafw/asakusafw,cocoatomo/asakusafw,ashigeru/asakusafw,akirakw/asakusafw,cocoatomo/asakusafw,ashigeru/asakusafw