NIAD-3449: updating documentation about Spine Secure Proxy

[ORybak5]

What

Documentation updates about the access to Spine Secure Proxy according to https://digital.nhs.uk/services/gp-connect/develop-gp-connect-services/integrate-with-spine/spine-secure-proxy guide

Why

Documentation should reflect the actual state of the workflows in the application

Type of Change

Please check the option(s) that apply.

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Internal change (non-breaking change with no effect on functionality affecting end users)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have updated the Changelog with details of my change in the UNRELEASED section, if this change will affect end users

[github-actions]

Images built and published to ECR using a Build Id of PR-321-3cc0ed2

[github-actions]

Images built and published to ECR using a Build Id of PR-322-1eacd00