Add -f option for customizing output filename

[pierre-sion]

Hello Michael,

I would like to suggest an improvement to dbdoclet so that the name of the generated DocBook file is not hard-coded as "Reference.xml", but configurable through a command-line option "-f". I made the changes in the source code, and I will send you by email the relevant Java class files: AbstractDoclet, DocBookDoclet, DocletOptions (we are not allowed to attach source code to a Github issue)

Best regards,
Pierre Sion

[mfuchs23]

Hello Pierre,

thank you very much for your improvement, I will incorporate it into the next release.

Regards,
Michael