Create testing examples

[sztadii]

Hi, before I will start I need to say thank you for the very nice and easy-to-learn package.
I am coming from the Node ecosystem, but the team decided to use Python, so we choose Ariadne to run our project :)
And I need to say was very easy to start with ( even for Python newbie )

What do you think if we can add some nice testing examples to the docs, so the new Ariadne users will able to start to write production and testable code much faster?