Explain each submodule update step
Explain each submodule update step

To give some context of why each step is needed and to prepare for
breaking out the feedstocks repo updates to a webservice, add some
comments explaining why each step is needed.

conda-forge/conda-forge.github.io,conda-forge/conda-forge.github.io,conda-forge/conda-forge.github.io,conda-forge/conda-forge.github.io