doxygen: set WARN_IF_UNDOC_ENUM_VAL = YES

Author: eramongodb

Doxyfile

@@ -883,7 +883,7 @@ WARN_NO_PARAMDOC       = NO
 # will automatically be disabled.
 # The default value is: NO.
 
-WARN_IF_UNDOC_ENUM_VAL = NO # TODO: set to YES.
+WARN_IF_UNDOC_ENUM_VAL = YES
 
 # If the WARN_AS_ERROR tag is set to YES then doxygen will immediately stop when
 # a warning is encountered. If the WARN_AS_ERROR tag is set to FAIL_ON_WARNINGS