Add missing documentations

[njoubert-cleverage]

Description

• Complete reference for RequestTask, add missing RequestTransformer reference and SOAP clients (cleverage.soap.client)
• Add cookbooks (e.g. call a SOAP service and map the response)

Requirements

• Documentation updates
  • Reference
  • Cookbooks
  • Changelog
• Unit tests

Breaking changes

Same as cleverage/process-bundle#145

[njoubert-cleverage]

Done in #24