Add notes for CONFIG_WPS_ER build configuration option

[Bug 407]

wpa_supplicant/README-WPS

@@ -62,6 +62,11 @@ CONFIG_DRIVER_NL80211=y
 CONFIG_WPS=y
 CONFIG_WPS2=y
 
+If you want to enable WPS external registrar (ER) functionality, you
+will also need to add following line:
+
+CONFIG_WPS_ER=y
+
 
 WPS needs the Universally Unique IDentifier (UUID; see RFC 4122) for
 the device. This is configured in the runtime configuration for

wpa_supplicant/defconfig

@@ -201,6 +201,8 @@ CONFIG_EAP_LEAP=y
 #CONFIG_WPS=y
 # Enable WSC 2.0 support
 #CONFIG_WPS2=y
+# Enable WPS external registrar functionality
+#CONFIG_WPS_ER=y
 
 # EAP-IKEv2
 #CONFIG_EAP_IKEV2=y