BibDocFile: FFT comment/description documentation

* Updates FFT documentation to harmonise the behaviour of file comments
  vs file descriptions, providing coherent usage example.  (closes #635)

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
Merge branch 'maint-1.0' into maint-1.1

* maint-1.0:
  BibDocFile: FFT comment/description documentation

Conflicts:
	modules/bibupload/doc/admin/bibupload-admin-guide.webdoc

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>