Add screen grab of Swagger docs to FastAPIWrapper page

[dantownsend]

Having a screen grab showing the generated Swagger docs would be nice on this page:

https://piccolo-api.readthedocs.io/en/latest/fastapi/index.html

The FastAPIWrapper / PiccoloCRUD combo is one of the most powerful things in the Piccolo ecosystem, and a screen grab will make it clearer the functionality it gives you.

That page is also unusual in that it uses Task as an example - we should change it to use Movie, as we can get example code / screen grabs from Piccolo Admin.

[sinisaos]

@dantownsend You can close this issue because it's done.