What is the Profile Manager? Needs documentation

[nlaws-camus]

The only place that the Profile Manager is referenced in the docs is
https://nrel.github.io/PyDSS/simulation_settings.html?highlight=profile%20manager#profilesmodel
and the default simulation.toml comes with

[profiles]
use_profile_manager = false
source_type = "h5"
source = "Profiles_backup.hdf5"
profile_mapping = ""
is_relative_path = true

For new users: what is a profile and what does the profile manager do?