some more about datasets
Merge branch 'feature/quickbookdoc' of https://github.com/boostorg/test into feature/quickbookdoc

# By Gennadiy Rozental
# Via Gennadiy Rozental
* 'feature/quickbookdoc' of https://github.com/boostorg/test:
  Ignore generate dfiles for now
  Clean up after the merge
  delete generated files for now
  Usage Variant and more structure changes
  Usage Variant and more structure changes
  Usage Variant and more structure changes