Added remark that the tb is self checking.

libraries/technology/ip_stratixiv/tse_sgmii_lvds/tb_ip_stratixiv_tse_sgmii_lvds.vhd

@@ -26,6 +26,8 @@
 --   Uniboard purposes in tb/ a minimal testbench tb_tse_sgmii_lvds.vhd was
 --   derived manually from the generated testbench. This tb_tse_sgmii_lvds
 --   is more easy to use.
+--   The tb is self checking based on that tx_pkt_cnt=rx_pkt_cnt must be true
+--   at the tb_end.
 -- Usage:
 --   > as 10
 --   > run -all