Add link to YouTube tutorials

[rfrenchseti]

• Fixes #1073
• Were any Django, import pipeline, table_schema, or dictionary files modified? Y
  • If YES:
  • Database used: opus3_test_200517
  • All Django tests pass: Y
  • FLAKE8 run on modified code: Y
• Were any JavaScript or CSS files modified? Y
  • If YES:
  • JSHINT run on all affected files: Y
  • Tested on Chrome, Firefox, Safari, Edge, and iOS: Y (Remember to test all browser sizes)
  • Tested for race conditions (with delayed API calls if applicable): NA

Description of changes:

Add tutorial video link to Help menu

Known problems: