Update README.md for Challenge 1 - Yearn Simple Strategy

[steve0xp]

Challenge 1 - Yearn Simple Strategy

• [x] Add emojis and walk through cleaning up copy and format (first pass)
• [x] Add checklists for tutorials like past challenge write-ups
• [ ] Possibly remove disclaimers and information about how this strategy was written up (or move them to main branch)
• [x] Final read through to ensure copy makes sense && back end challenge works as each steps outline
• [ ] Move onto new issue of coordinating front-end and scaffold-eth v2 into this challenge