added comment about x4

libraries/io/eth/eth.peripheral.yaml

@@ -26,7 +26,10 @@ peripherals:
       - mm_port_name: AVS_ETH_0_TSE
         mm_port_type: REG
         mm_port_span: 1024 * MM_BUS_SIZE # = c_tech_tse_byte_addr_w in tech_tse_pkg.vhd
-        mm_port_description: "Registers in the TSE IP [1], handled by the Nios microprocessor."
+        mm_port_description: |
+          "Registers in the TSE IP [1], handled by the Nios microprocessor.
+           Note that the address offsets are multiplied by 4 since the last
+           2 bits of the address signal are removed in VHDL."
         fields:
           - - field_name: rev
               field_description: |