Make doxygen not search files in all sub-directories

Author: asfernandes

doc/Doxyfile

@@ -57,7 +57,7 @@ ENUM_VALUES_PER_LINE   = 4
 TREEVIEW_WIDTH         = 250
 EXT_LINKS_IN_WINDOW    = NO
 FORMULA_FONTSIZE       = 10
-USE_MDFILE_AS_MAINPAGE = README.md
+USE_MDFILE_AS_MAINPAGE = @PROJECT_SOURCE_DIR@/README.md
 VERBATIM_HEADERS       = YES
 
 #---------------------------------------------------------------------------
@@ -161,12 +161,12 @@ EXCLUDE_SYMBOLS        = fbcpp::impl \
 EXAMPLE_PATH           =
 EXAMPLE_PATTERNS       = *
 EXAMPLE_RECURSIVE      = NO
-IMAGE_PATH             = @PROJECT_SOURCE_DIR@
+IMAGE_PATH             =
 INPUT_FILTER           =
 FILTER_PATTERNS        =
 FILTER_SOURCE_FILES    = NO
 FILTER_SOURCE_PATTERNS =
-USE_MDFILE_AS_MAINPAGE = README.md
+USE_MDFILE_AS_MAINPAGE = @PROJECT_SOURCE_DIR@/README.md
 
 #---------------------------------------------------------------------------
 # Source browsing related configuration options