README: clarify status of 802.3 support.

README.md

@@ -24,7 +24,7 @@ The only supported medium is Ethernet.
 
   * Regular Ethernet II frames are supported.
   * ARP packets (including gratuitous requests and replies) are supported.
-  * 802.3 and 802.1Q are **not** supported.
+  * 802.3 frames and 802.1Q are **not** supported.
   * Jumbo frames are **not** supported.
 
 ### IP layer