Add setup documentation

README.md

 # AMRDC Data Visualizer Synthesis
 
-Continued development of the "[amrdcdata-visualizer][original-repo]" web
+Continued development of the [`amrdcdata-visualizer`][original-repo] web
 app by Matthew Noojin.
 
-Demonstration: https://amrc.ssec.wisc.edu/ograham/visualizer-synthesis/visualizer.py/.
+Demonstration: https://amrc.ssec.wisc.edu/ograham/visualizer-synthesis/
 
+[original-repo]: https://github.com/mnooj/amrdcdata-visualizer
 
 
-[original-repo]: https://github.com/mnooj/amrdcdata-visualizer
+
+## Setup
+
+
+### As CGI on Apache
+
+#### Clone
+
+Clone this repository to a directory outside of the Apache document
+root.
+
+> On `amrc`, it's cloned to `~ograham/visualizer-synthesis/`.
+
+#### Install virtual environment
+
+Run `virtualenv venv` in the project directory to create the virtual
+environment `venv`.
+
+> `virtualenv` can be installed with `pip3 install virtualenv`.
+
+Activate `venv` and run `pip install -r requirements.txt`.
+
+> To activate `venv` with bash or zsh, run `. ./venv/bin/activate`.
+
+#### Link
+
+Create a symbolic link, with the desired path under the document root,
+to the `htdocs` directory in this repository.
+The Apache configuration will have to allow such links outside of the
+document root, as well as all rules in `htdocs/.htaccess`.
+
+> On `amrc`, the web path is `/ograham/visualizer-synthesis/` and the
+> document root is `/data/web/amrc/htdocs`, so the linking command is
+> `ln -sT ~ograham/visualizer-synthesis/htdocs /data/web/amrc/htdocs/ograham/visualizer-synthesis`.
+
+
+### As a Heroku app
+
+This repository is also ready to go as a Heroku Python app.