Generate a better OpenAPI description from docstring

[antoine-roux]

As this PR is a minor one, I'm skipping the issue creation. Please forgive me...

Context

If a docstring is well indented (often automatically by black or other) the generated description for OpenAPI will contains indentation, which is not desirable. Markdown will interpret this indentation as code block:

        """Summary

        Description line 1

        Description line 2
        """

generates

Description line 1\n\n        Description line 2

with this PR, the generated MD would be

Description line 1\n\nDescription line 2

Have a nice day :)
Antoine

[greyli]

Hi, thanks for working on this! Could you add some tests?