refine conf

@@ -937,7 +937,9 @@ vhost with-hls.srs.com {
         # default: off
         hls_ts_floor    off;
         # the hls entry prefix, which is base url of ts url.
-        # if specified, the ts path in m3u8 will be like:
+        # for exmaple, the prefix is:
+        #         http://your-server/
+        # then, the ts path in m3u8 will be like:
         #         http://your-server/live/livestream-0.ts
         #         http://your-server/live/livestream-1.ts
         #         ...