Improve documentation around updating terraform configuration files

[Collinbrown95]

Description

There has been some confusion around the steps required to update the various AAW terraform repositories. It would be good to have a short snippet of documentation somewhere indicating the steps involved with updating AAW terraform modules.

[Collinbrown95]

Discussion Points

• Consider adopting "latest" reference to a particular branch as the trigger for mirroring to github rather than a git tag - should have a discussion about what this refactor would look like.
• Consider updating documentation indicating the various dependencies for the aaw-dev-cc-00 and aaw-prod-cc-00 terraform modules (all the way to root modules like network and environment).
• Consider adding instructions for how to go through an update to the terraform. Consider adding a README with examples - include example for updating node pool + subnet - can have a ticket to formalize that documentation later.

[Collinbrown95]

Documentation for adding node pool updated here https://gitlab.k8s.cloud.statcan.ca/cloudnative/aaw/terraform-advanced-analytics-workspaces-infrastructure/-/tree/collin.brown-main-patch-38858#add-a-new-node-pool-and-subnet