Backend für "Kommentar/Remark Feld für Empfänger"

Related issues

Closes #64 Related to the ticket 76 in the front-end

Acceptance criteria

• Implemented code changes don't diverge from the related issue.
• Documentation reflects the status quo after merge.
• Version number is incremented according to SemVer. (Snapshot versions are not merged/released.)
• Only released versions of dependencies are used (i.e. no snapshot versions).
• Pipeline still works.
• GitLab issue is up-to-date.

If necessary, the following sections have been updated:

• Swagger
• Readme.md
• Documentation

Proposed squash commit message

Modify PDF to show consinee remarks 

* Consignee remarks (reservations/observations)
  are shown rigth to the consignee signature

Co-authored-by: Nettie Chau

Closes #64