Add getting started tutorial for CLI and registry-service

[mwyzhao]

Something like:

1. building service-registry
2. setting up a registry cluster via registry-service (bootstrap setup can link to the bootstrap/monitor docs)
3. creating a container and adding it via registry-cli
4. verifying success via registry-cli

[mwyzhao]

Another suggestion is to add separate tutorials for registry-cli and registry-service and add them to their respective directories. The top-level README can just have a brief overview and point to the respective directories for usage.

[hivanco]

The PhysarumSM Getting Started Guide has been updated with instructions regarding using service-registry. I'll still add more detailed docs for registry-cli and registry-service here.