Obsolete documentation

Documentation https://git.jinr.ru/dnaumov/ntsim/-/wikis/Usage advises to use ntsim.ntsim module, which seems to be obsolete. In particular it uses h5Writer while the current module and class name is H5Writer.

Suggestion:

1. Move ntsim/ntsim.py it to obsolete directory (for this release, and delete it completely in the future release)
2. Rename ntsim/ntsim_2.py to ntsim/ntsim.py
3. Add a more detailed usage example in the documentation - showing a simple simulation end-to-end, so the user could see that it's working