Add 2 new articles on GPT-3

[akshay kadam (a2k)]

These were really good 👌

https://blog.andrewcantino.com/blog/2021/04/21/prompt-engineering-tips-and-tricks/

https://blog.andrewcantino.com/blog/2021/05/28/how-to-dramatically-improve-the-reasoning-ability-of-GPT-3/