[DOCS] Development environment setup

[jerdra]

Development environment setup for airflow is tricky because it requires a back-end database and some data + services be available in order to test in the development environment. Setting up a DEV environment therefore requires documentation so that contributors can get up to speed quickly with minimal configuration and setup.

For details see #17

[jerdra]

ok so I've done a bit of reading + thinking on this topic and I'm leaning towards implementing our DEV environment in a completely separate repo. I like the approach here:

https://www.numeratorengineering.com/microservice-dev-environments/

In summary, applying the above:

• We'd keep airtigrs-docker-compose as a separate repository for spinning up development environments
• Extensions (i.e dashboard, airtigrs, xnat, sftp, redcap) will be implemented as submodules containing a Dockerfile
• I'm still learning/figuring out whether it's better to have a single docker-compose vs. multiple docker-compose..yml files. I'm leaning toward the latter since our separate services aren't actually tightly coupled and can be configured using our central main_config.yaml file anyway

Also moving forward, what do ppl think about porting over all discussion surrounding development environments to https://github.com/tigrlab/airtigrs-docker-compose?