chore: update documentation

[tomguilbert]

What needs doing?

As noted in https://github.com/epimorphics/frontend-backlog/issues/114 update the documentation for this app - especially how to deploy

Kind

Documentation

Why now?

No response

Done when

The following are addressed in the app's documentation:

• e2e tests are written and work via GitHub action, but will not pass on hmlr-pres-dev because the machines are not powerful enough to complete large queries. We should confine them in that case to preprod. Consider limiting the e2e tests to the preprod environment in the action (or providing a set list of one environment to choose from)
• if tests require a password to access the environment, consider adding as a GitHub secret.
• deployments (Ansible) should not happen concurrently. Any in flight deployments should be allowed to complete before beginning another
• add table of environments and their URLs to each README. Add directions for developers to find the username and passwords for the environments.
• update the reusable workflows used to their latest versions.
• describe the tools for container observability: where to find, how to interpret...