ENH: Added .dox extension to doxygen file patterns

doc/Doxygen/Doxyfile

@@ -608,7 +608,8 @@ INPUT_ENCODING         = UTF-8
 # *.hpp *.h++ *.idl *.odl *.cs *.php *.php3 *.inc *.m *.mm *.py *.f90
 
 FILE_PATTERNS          = *.H \
-                         *.C
+                         *.C \
+                         *.dox
 
 # The RECURSIVE tag can be used to turn specify whether or not subdirectories
 # should be searched for input files as well. Possible values are YES and NO.