list the package managers configured by this action

It would be good to provide a list of the package managers that this action configures.

I.e:
* `conda`
* `miniconda`
* `mamba` [1]
* `micromamba` [1]
* `pip`

Any possibly:
* `pipenv`?
* `poetry`?

> [1] https://github.com/MetOffice/action-setup-artifactory/pull/24

Review the action configuration to verify which package managers it configures, then check the existing project documentation for the appropriate list location. Document the confirmed managers and resolve whether pipenv and poetry are supported; done when the documentation accurately lists the configured managers.

Written by the indexing model from the issue text.