Switch example API to from GitHub to Typicode JSON example api

[robinheinze]

This is for #92

Quote for convenience:

"Github has a really great, robust REST API.

However, it doesn't feel like it makes the most ideal example API for Ignite.

- Repos aren't super relatable as a data type, compared to, say, users
- It has some custom configuration, like it's custom Content-Type: application/vnd.github.v3+json which can be confusing if you're trying to transform our example into your own API service .

I'm proposing switching the sample API to https://jsonplaceholder.typicode.com/, which is designed to be a sample, and supports straight REST endpoints for data types like users, todos, posts and other familiar example concepts."

[skellock]

Thx Robin