Fix commentary (#7800)

Minor fix based on observation done in https://github.com/espressif/arduino-esp32/issues/7795#issuecomment-1416868611

libraries/Ethernet/src/ETH.cpp

@@ -392,7 +392,7 @@ bool ETHClass::begin(uint8_t phy_addr, int power, int mdc, int mdio, eth_phy_typ
         log_e("esp_eth_init error: %d", err);
     }
 #endif
-    // holds a few microseconds to let DHCP start and enter into a good state
+    // holds a few milliseconds to let DHCP start and enter into a good state
     // FIX ME -- adresses issue https://github.com/espressif/arduino-esp32/issues/5733
     delay(50);