Add new resources for learning web3

[kartikver15gr8]

Contribute to this repo by adding new resources to it✍

[karan79k]

These are three open sources to learn web 3

1. Growth school
2. Dapp university
3. EDX

[kartikver15gr8]

You have to add them into the README.md file and then send a pull-request, and then I'll check them and merge.