Update comment in Dockerfile

Author: romainx

base-notebook/Dockerfile

@@ -29,8 +29,9 @@ ARG conda_version="4.9.2"
 ARG miniforge_patch_number="7"
 # Miniforge installer architecture
 ARG miniforge_arch="x86_64"
-# Python implementation to use 
-# can be either Miniforge3 to use Python or Miniforge-pypy3 to use PyPy
+# Package Manager and Python implementation to use (https://github.com/conda-forge/miniforge)
+# - conda only: either Miniforge3 to use Python or Miniforge-pypy3 to use PyPy
+# - conda + mamba: either Mambaforge to use Python or Mambaforge-pypy3 to use PyPy
 ARG miniforge_python="Mambaforge"
 
 # Miniforge archive to install