docs: add api collection and update readme for data exchange tutorial

[mgarciaLKS]

Description

Issue #151
This PR contains the updates in the README file concerning the Data Exchange Tutorial using the SSI DIM WALLET STUB.
Also created some folders related to the docs, that contains both the Postman Collection and the Curl tutorial.

Pre-review checks

Please ensure to do as many of the following checks as possible, before asking for committer review:

• DEPENDENCIES are up-to-date. Dash license tool. Committers can open IP issues for restricted libs.
• Copyright and license header are present on all affected files

[evegufy]

Looks really good! Just some comments.

Could you please remove this warning, it's obsolete since the stub has been integrated.

[mgarciaLKS]

@evegufy As always, thank you for the time invested in this immersive correction, I have fixed the bugs and answered the ones where I had some doubts, thank you. 💪

[CDiezRodriguez]

To get the simple-data-backend ingress up and running, you’ll need to do two things:

1. Add this to your values.yaml:

  simple-data-backend:
    nameOverride: dataprovider-submodelserver
    ingress:
      enabled: true
      className: "nginx"
      hosts:
        - host: "dataprovider-submodelserver.tx.test"
          paths:
            - path: "/"
              pathType: "Prefix"

2. Add this line to your /etc/hosts file:

192.168.49.2    dataprovider-submodelserver.tx.test

[mgarciaLKS]

Thanks, @evegufy for the response.
Sorry for all the commits, thought it worked differently when accepting a change, Will do different in the next PR.
I have tested the data exchange with the new Backend and values and worked fine for me. However, the new service is not fully functional, e.g. these calls are not available, it might be interesting to add them in the future:

   "privateProperties": {
      "receiverHttpEndpoint": "{{BACKEND_SERVICE_PROTOCOL}}/api/v1/transfers"
   },

[evegufy]

Thanks, @evegufy for the response. Sorry for all the commits, thought it worked differently when accepting a change, Will do different in the next PR. I have tested the data exchange with the new Backend and values and worked fine for me. However, the new service is not fully functional, e.g. these calls are not available, it might be interesting to add them in the future:

   "privateProperties": {
      "receiverHttpEndpoint": "{{BACKEND_SERVICE_PROTOCOL}}/api/v1/transfers"
   },

Hi @mgarciaLKS thank you! I can't really judge the impact of the simple data backend not being fully functional. Is it still possible to go through all steps of the tutorial?

[evegufy]

Hi @mgarciaLKS looks very good! I just did some final adjustments. Thank you!