first add sdk

component/common/example/pppoe/readme.txt

@@ -0,0 +1,21 @@
+LWIP PPPOE EXAMPLE
+
+Description:
+Example for lwip pppoe connection.
+
+Configuration:
+[lwipopts.h]
+    #define PPP_SUPPORT                     1
+    #define PPPOE_SUPPORT                   1
+    #define PPPOS_SUPPORT                   0
+    #define PAP_SUPPORT                     1
+    #define CHAP_SUPPORT                    1
+    #define MD5_SUPPORT                     1
+[platform_opts.h]
+    #define CONFIG_EXAMPLE_PPPOE            1
+
+Execution:
+Can make automatical Wi-Fi connection when booting by using wlan fast connect example.
+A PPPOE example thread will be started automatically when booting.
+
+Setup PPPOE_USER and PPPOE_PASSWD in example_pppoe.c for authentication. PPP addresses will be shown after PPP is connected