Introducing conda in the setup page

[tbooth]

from @tkphd

Conda is a common and useful tool, but it is simply invoked, not introduced. Explain what it is (a Python distribution with virtual environment isolation), how it helps (simplifies dependency management), and how to use it.

The instructions as written appear to update an existing environment, not create a new one. The environment is named "snakemake_dash". Why? The conda_env.yaml file contains a whole lot of specific packages. Consider filtering this to specify just those packages you would install manually: snakemake, fastqc, kallisto, etc. Let conda fill in the full dependency graph.