net: Replace "Supported NIC models" with "Available NIC models"

Just because a NIC model is compiled into the QEMU binary does not
necessary mean that it can be used with each and every machine.
So let's rather talk about "available" models instead of "supported"
models, just to avoid confusion.

Reviewed-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/net.c

@@ -941,7 +941,7 @@ int qemu_show_nic_models(const char *arg, const char *const *models)
         return 0;
     }
 
-    printf("Supported NIC models:\n");
+    printf("Available NIC models:\n");
     for (i = 0 ; models[i]; i++) {
         printf("%s\n", models[i]);
     }