Add an example folder with a nestjs app ready to use.

[0xslipk]

I'm submitting a...

[ ] Regression 
[ ] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

Expected behavior

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Environment

Nest version: X.Y.Z
Nest Ethers version: X.Y.Z

 
For Tooling issues:
- Node version: XX  
- Platform:  
- Server:  

Others: