[p] Improve mail templates

- Add contract UUID
- Fix typos
3 jobs for add-uuid-in-contract-signature-invitation-17
Status Job ID Name Coverage
  Test
passed #2084
golang lint
Code lint

00:07:16

passed #2083
golang mongo goqt
Integration tests

00:02:30

passed #2082
golang mongo strong
Unit tests

00:02:36