For installing Conda packages on Linux: insist on using a fresh Conda environment

[popescu-v]

When installing from conda-forge, the latter's documentation recommends to always use a fresh new Conda environment instead of the base environment:

• https://conda-forge.org/docs/user/introduction/
• https://conda-forge.org/docs/user/tipsandtricks/

On the Khiops installation page related to Conda, one should also reiterate the same recommendation clearly.