polish Install and Setup

[kelle]

• Readme Title should be consistent with folder name. E.g., change Readme title to "Setup and Install Instructions for Workshop"
• make it even more clear where commands should be typed (e.g., in Terminal vs in Jupyter Notebook).
• make it even more clear what directory one should be in when typing commands. e.g., add cd and/or pwd commands.
• be explicit about which directory to be in when opening the notebook.

[stargaser]

To add to the list: a bash shell is no longer needed to use conda.

[eblur]

Need install instructions to address zsh setup in new Mac OS

[mwcraig]

Steps to deal with zsh:

source /path/to/conda/bin/activate
conda init zsh

Then open a new terminal window and conda list should give some kind of sensible output.

[kelle]

also consider adding something about 32-bit/64-bit discussed in #54.

[kelle]

Copied and pasted from #170: Give conda environment a different name:

The workshop repository is named astropy-workshop and the conda environment has the same name. When changes need to be pulled from the repository, and new packages or updated packages need to be installed into the conda environment, it is easy to conflate these two locations.

Change the conda environment name to something different, like astropy-env.