Remove API doc entry

swagger got removed a while ago while packging it for debian:stable due
to older django version. Unfortunately removing the swagger API in the
doc got not removed.

README.md

@@ -13,7 +13,6 @@ Or in this case personification of a service to generate reports.
 - [Installation](#installation)
   - [Requirements](#requirements)
 - [Development](#development)
-- [API overview](#api-overview)
 - [Maintainer](#maintainer)
 - [Contributing](#contributing)
 - [License](#license)
@@ -57,16 +56,6 @@ Validate the activated git hooks by running
 
     poetry run autohooks check
 
-## API overview
-
-To get an overview of the API you can start this project
-
-```
-poetry run python manage.py runserver
-```
-
-and then go to [swagger](http://localhost:8000/docs/)
-
 ## Usage
 
 In order to prepare the data structure the XML report data needs to be posted to `pheme` with a grouping indicator (either by host or nvt).