Add some of the .txt files in /doc subdir to doxygen documentation

doc/doxygen/contrib.h

@@ -0,0 +1,4 @@
+/**
+ * @page contrib How to contribute to lwIP
+ * @verbinclude "contrib.txt"
+ */

doc/doxygen/lwip.Doxyfile

@@ -781,7 +781,7 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = ../../src main_page.h
+INPUT                  = ../../src main_page.h rawapi.h ppp.h contrib.h sys_arch.h
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
@@ -875,7 +875,7 @@ EXCLUDE_SYMBOLS        =
 # that contain example code fragments that are included (see the \include
 # command).
 
-EXAMPLE_PATH           =
+EXAMPLE_PATH           = ../
 
 # If the value of the EXAMPLE_PATH tag contains directories, you can use the
 # EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp and

doc/doxygen/ppp.h

@@ -0,0 +1,4 @@
+/**
+ * @page ppp PPP
+ * @verbinclude "ppp.txt"
+ */

doc/doxygen/rawapi.h

@@ -0,0 +1,4 @@
+/**
+ * @page rawapi RAW API
+ * @verbinclude "rawapi.txt"
+ */

doc/doxygen/sys_arch.h

@@ -0,0 +1,4 @@
+/**
+ * @page sys Porting (sys abstraction layer)
+ * @verbinclude "sys_arch.txt"
+ */

src/include/lwip/raw.h

@@ -1,6 +1,7 @@
 /**
  * @file
- * raw API (to be used from TCPIP thread)
+ * raw API (to be used from TCPIP thread)\n
+ * See also @ref rawapi
  */
 
 /*

src/include/lwip/tcp.h

@@ -1,6 +1,7 @@
 /**
  * @file
- * TCP API (to be used from TCPIP thread)
+ * TCP API (to be used from TCPIP thread)\n
+ * See also @ref rawapi
  */
 
 /*

src/include/lwip/udp.h

@@ -1,6 +1,7 @@
 /**
  * @file
- * UDP API (to be used from TCPIP thread)
+ * UDP API (to be used from TCPIP thread)\n
+ * See also @ref rawapi
  */
 
 /*