add logo images

Author: shengwen-tw

docs/Doxyfile

@@ -51,7 +51,7 @@ PROJECT_BRIEF          = "A Linux-like Real-Time Operating System for Robotics a
 # pixels and the maximum width should not exceed 200 pixels. Doxygen will copy
 # the logo to the output directory.
 
-PROJECT_LOGO           = logo.png
+PROJECT_LOGO           = docs/images/logo-small.png
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) path
 # into which the generated documentation will be written. If a relative path is