Improve doxygen documentation

Add timestamp to the html output.

doxygen/cbmDoxyfile.conf

@@ -66,6 +66,7 @@ HTML_FILE_EXTENSION    = .html
 HTML_HEADER            = 
 HTML_FOOTER            = 
 HTML_STYLESHEET        = 
+HTML_TIMESTAMP         = YES
 HTML_ALIGN_MEMBERS     = YES
 GENERATE_HTMLHELP      = NO
 GENERATE_CHI           = NO
@@ -80,7 +81,7 @@ ENABLE_PREPROCESSING   = YES
 MACRO_EXPANSION        = NO
 EXPAND_ONLY_PREDEF     = NO
 SEARCH_INCLUDES        = YES
-INCLUDE_PATH           = $ROOTSYS/include
+INCLUDE_PATH           = $(ROOTSYS)/include
 INCLUDE_FILE_PATTERNS  = 
 PREDEFINED             = 
 EXPAND_AS_DEFINED      =