Changes to rustic config

[simonsan]

I think it might be also confusing to have [[backup.sources]] multiple times and then to have a field called source which takes multiple values again.

The field should probably be renamed to sources and the table name to [[backup.source-groups]] or something. So it's clearer. Then sources takes an array of paths: ["/path/1/2", "path/3/4"].

Originally posted by @simonsan in #1094 (comment)

• since fix(config)!: multiple paths in config profile as array #1124 source is now an array