Is there a way to manage public API documentation?
So far as I know for community driven modules only the Services module has support to autogenerate API documentation via the Services Documention module. If you've been the D7 public API without using Services ... then you may be out of luck.


  The Services Documentation module generates API documentation for your
  site’s Services resources. Most of the documentation is generated
  automatically, using the resource information provided by Services.
  However, this module provides you with the ability to easily extend
  that documentation.
  
  We make the following assumptions about your usage of the Services
  module:
  
  
  You are providing an API to a third party, which allows them to access
  your data via Services.
  You would like to provide a page to API
  consumers that documents your API endpoints, resources, etc.
  
  
  Documentation will be made available on your Drupal site at
  /developers.
  It will be organized by API version (arbitrarily defined
  by you), and subsequently displayed hierarchically according to
  resource, method type, method name, arguments, etc.