Add doc/ directory and .S files.

src/doxygen.cfg

@@ -60,8 +60,12 @@ WARN_LOGFILE           =
 #---------------------------------------------------------------------------
 INPUT                  = @SRCDIRS@ \
                          include \
-                         arch/@ARCH@/include
-FILE_PATTERNS          = 
+                         arch/@ARCH@/include \
+                         doc
+FILE_PATTERNS          = *.c \
+                         *.h \
+                         *.S \
+                         *.dox
 RECURSIVE              = NO
 EXCLUDE                = 
 EXCLUDE_SYMLINKS       = NO