Added eplanation of link fault operation.

libraries/technology/eth_10g/tech_eth_10g_arria10.vhd

@@ -56,6 +56,14 @@
 --    0 = OK
 --    1 = local fault
 --    2 = remote fault
+--
+--  From google search:
+--    Link fault Operation
+--    1) Device B detects loss of signal. Local fault is signaled by PHY of Device B to Device B.
+--    2) Device B ceases transmission of MAC frames and transmits remote fault to Device A.
+--    3) Device A receives remote fault from Device B.
+--    4) Device A stops sending frames, continuously generates Idle.
+--
 --  Hence when the xgmii_link_status is OK then the other side is also OK so
 --  then it is also appropriate to release tx_snk.xon.
 --