• add version
• remove separator

1. By adding a simple string (eg. "v0.11.0\n") we should be able to correctly handle different versions and avoid breaking stuff, therefore, providing a nice user exp.

Other projects doing that:

• Tarantool https://tarantool.org/doc/1.7/dev_guide/internals_index.html#xlog-snap

2. We don't really need a separator unless we have complex structures (rows, cells like RDBMS have https://www.sqlite.org/fileformat.html). Or do we? Need to think more about it.