Merges rcpch/digital-growth-charts-documentation site into the dGC server repo

[pacharanero]

This is a complete merge of the rcpch/digital-growth-charts-documentation site into the dGC repository.

The purpose of this merge is to bring the docs site 'closer' to one of the main dGC repos, meaning that it will be easier to make docs site changes while editing other code.

In local development we have optimised towards using Docker Compose to run the FastAPI and Material for MkDocs containers (both built from the same image as they are very similar)

For deployment, each service is deployed via a GitHub Action to separate Azure Web Apps (a Static Web App in the case of the Docs site)

The PR contains the entire Git history of the original docs site so there are a very large number of commits. However the bulk of the documentation has not been changed at all from the other repo, we just merged it into place here in this repo.

When merged, this PR closes the following Issues:

• closes Merge the documentation site into one of the other dGC repos digital-growth-charts-documentation#96
• closes Dockerize documentation so that it is easier and more consistent for new developers digital-growth-charts-documentation#95
• closes Docker and dgc documentation digital-growth-charts-documentation#101
  (as these Issues are in a different repo we may not be able to rely upon GitHub auto-closing these when merged, so please check)

IMPORTANT

• All other Issues on the docs site repo NEED TO BE TRANSFERRED TO THIS REPO and then labelled something like documentation

[github-actions]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://red-mud-064bedc03-209.westeurope.4.azurestaticapps.net

[anchit-chandran]

Have just also made content updates:

• Updates docker development documentation
• Updates to developing the documentation site
• Update all instances of signal / openhealthhub to discourse (except for a couple places which referred to articles that aren't present on the discourse)

[github-actions]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://red-mud-064bedc03-209.westeurope.4.azurestaticapps.net

[github-actions]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://red-mud-064bedc03-209.westeurope.4.azurestaticapps.net

[mbarton]

I'm happy with this approach, thanks for the consolidation!

[pacharanero]

@mbarton are you happy for me to merge this today? AFAICT there's no changes which would affect the dGC server itself, only documentation additions. Tests are all passing, and the Azure deployment GitHub Workflow for dGC Server is unchanged apart from updates of the Actions versions.

With these changes, we are strongly encouraging the use of the Docker Compose setup for dGC Server development, but that is not going to affect deployment.

[mbarton]

Go for it

[pacharanero]

In the process of preparing to merge this I have found some issues with the Pydantic upgrade done a few weeks back so this PR is on hold until we have that a little more sorted out

[mbarton]

This change needs porting across to this PR before merging: rcpch/digital-growth-charts-documentation#105