Changelog for Vestnik.

3.0.1-pl
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- Email attachments: pass the reserved `attachments` key (list of file paths or {file, name} pairs) in trigger() $data or snippet &data
- New system setting vestnik_attachments_path restricts the directory attachments may be taken from (empty = site root)
- Queue email preview shows the list of attachments
- Docs tab: new "Attachments" section

3.0.0-pl
==============
- The first release
