I'm starting to use the project with the newly release 3 version.


https://github.com/spec-first/connexion/blob/70084bcc4c21713cbf861841ebda977263d3ab8c/docs/middleware.rst?plain=1#L115-L120

It seems this example is not correct. 

1. missing import for SecurityMiddleware
2. `ConnexionMiddleware.default_middlewares` is a list of classes, not
class instances: the filtering never happen.

Fixes #1797 

[Relevant
docs](https://docs.readthedocs.io/en/stable/guides/edit-source-links-sphinx.html#github).

Fixes #1806
Fixes #1811

Updates the import statements on
https://connexion.readthedocs.io/en/stable/cookbook.html


A few of the import statements were missing, or didn't match the example
code because they imported at the wrong depth.
This should make the code in the cookbook copy-pasteable.

---------

Co-authored-by: Robbe Sneyders <robbe.sneyders@gmail.com>

As discussed in #1807.

Allowing the injection of WSGI middleware can enable easier migration
from Connexion 2 to Connexion 3. The use cases are limited though, as
this will only work for middleware that can work at the end of the
middleware stack.

Fixes #1794
Fixes #1802