Make frontend demo and update README.md

[iamgeeyuh]

• show programs page
• show draggability of workouts inside program
• show sharing document feature
• show calendar (after putting in realistic dummy data)
• show workout logging

[iamgeeyuh]

create a short video highlighting each feature:

• show program creation
  • show drag and drop
  • show program saving
• show program access level
• show calendar