docfile-like builtin for filename only

[IanDarwin]

The docfile built-in attribute actually produces the full path rather than the file, e.g,.
/Users/ian/workspace/project/src/doc/ref/intro/0105-bleah.adoc.

It would be nice if there were a way to directly get just the filename, 0105-bleah.adoc

[mojavelinux]

You can get the basename from the attribute "docname". In your case, it would be "0105-bleah". If you always use .adoc as the AsciiDoc file extension, you can build it using {docname}.adoc.

I suppose we should add an attribute for infilesuffix (to complement outfilesuffix). Do you like that idea?

[IanDarwin]

Ah, docname isn't in the reference manual so I didn't see it. Thanks!

I'm less concerned about the file suffix.

[mojavelinux]

Thanks for pointing that out @IanDarwin. I added it to the user manual.

I think we should still add docfilesuffix (rather than infilesuffix) for completeness.