Refactor file export

[Stratis-Dermanoutsos]

Describe the bug -
For now, exported files have unclear names.

Expected behavior -
The year and month targeted for the export should be immediately understood by the name of the file so it's clear what the content will be before opened.

Additional context -
Probably revert back to the old naming

<year>/<month-index>-<month-fullname>.md

# e.g.
2023/01-January.md