Adding applications examples

[leonarf]

Problem

There was a todo in the documentation with a list of example to fill

Solution

I Added my_webapp as example of packaging a PHP application
I also added FastAPI as example of packaging a python application

I use both applications, and their code is light so I think they are good application to start packaging other PHP or python app's

PR checklist

• I'm not doing a PR for an application, I promise, I know that this kind of changes must go directly into the app packages themselves
• PR finished and ready to be reviewed