Flag first transcriptions in Slack

[itsthejoker]

Relevant issue: #133

Description:

Modifies the transcription check request to be obvious when it's someone's first transcription.

Checklist:

• [x] Code Quality
• [x] Pep-8
• [x] Tests (if applicable)
• [x] Success Criteria Met
• [x] Inline Documentation
• [ ] Wiki Documentation (if applicable)