Simplify handling optional arguments
Remove some AUTOMATIC_DOCUMENTATION.enable_documentation checks

These are redundant since AutoDoc_CreateCompleteEntry already
checks AUTOMATIC_DOCUMENTATION.enable_documentation.
Pass the return code of AutoDoc_CreateCompleteEntry through

This seems to be the sane thing to do, and might help with error
handling in the future.
doc/title.xml: remove useless 'date'

The version already encodes the date, and this field is
easy to forget during an update.
Add myself to manual, too