Document hydromt install via deltaforge

[hboisgon]

HydroMT version checks

• [X] I have checked that the issue still exists on the latest versions of the docs on main here

Kind of issue

Docs are missing

Location of the documentation

Installation guide

Documentation problem

For users that are not familiar with python, HydroMT and some of its plugins are available to install using Deltaforge.

Maybe we can decide to document this download and install option in our docs?

Another use case to install like this is for example, as we do not have an executable, for external tools like Delft-FEWS, this makes install, deployment and use easier than classic python installation and use.

Suggested fix for documentation

Decide if we want to document or link Deltaforge in our installation guide documentation.