hostapd: Add comment about CONFIG_FULL_DYNAMIC_VLAN to defconfig

Add comment about CONFIG_FULL_DYNAMIC_VLAN to defconfig. By default
this feature is still disabled.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>

hostapd/defconfig

@@ -153,6 +153,10 @@ CONFIG_IPV6=y
 # Remove support for VLANs
 #CONFIG_NO_VLAN=y
 
+# Enable support fur fully dynamic VLANs. This enables hostapd to
+# automatically create bridge and VLAN interfaces if necessary.
+#CONFIG_FULL_DYNAMIC_VLAN=y
+
 # Remove support for dumping state into a file on SIGUSR1 signal
 # This can be used to reduce binary size at the cost of disabling a debugging
 # option.