Update documentation to clarify SpringContainerMS data model for City objects & creation of containers

[osowski]

Update the documentation to include specifics on why the City object in the SpringContainerMS data model has two lat/long pairs. This is used when a container is created, as the application will look up the City and ensure there is a City bounding box that contains the new Container lat/long location. If not, the SpringContainerMS microservice will throw an error.