Rewrite comments to improve clarity

src/iocore/net/UnixNetVConnection.cc

@@ -574,11 +574,10 @@ UnixNetVConnection::net_read_io(NetHandler *nh)
       return;
     }
 
-    // We should only splice once to the pipe
-    // Linux splice() does not merge pipe buffer page so there is no guarantee that we can splice to pipe again
-    // without receiving EAGAIN from pipe even if data_in_pipe < pipe_capacity
-    // Disable read until consumer finish a successful splice from pipe to socket operation
-    // which means there are available pages in the pipe
+    // We should only splice once to the pipe until the pipe is cleared by consumer
+    // Linux splice() does not merge pipe buffer page so there is no guarantee that
+    // we can splice to pipe again without receiving EAGAIN from pipe even if data_in_pipe < pipe_capacity
+    // Disable read until consumer finish a successful splice from pipe to socket operation and the pipe is empty
     read_disable(nh, this);
     return;
   }