Add basic myst/sphinx site building instructions to README.

Author: rossbar

README.md

@@ -29,6 +29,41 @@ However, we add it here that you can easily have the same user experience in Jup
 - Document an accessible development workflow, so that non-experts can contribute.
 - Keep the infrastructure as simple as possible.
 
+## Build the site
+
+There are currently two distinct technology stacks that support the
+`executable-tutorials` paradigm: a legacy sphinx-based static-site generation
+engine, and the newer [myst][myst-org] project.
+The `executable-tutorials` repo contains information about both development
+patterns, and endeavors to serve as a transition guide between technology
+stacks.
+
+By default, the necessary tooling for both technology stacks is installed with
+`pip install -r requirements.txt`
+
+### Build with sphinx
+
+```bash
+make html
+```
+
+The static site can then be viewed by simply opening the index in any browser,
+for example::
+
+```bash
+firefox _build/html/index.html
+```
+
+### Build with `myst`
+
+```bash
+myst start --execute
+```
+
+This will execute the notebooks, build the site, and set up a server for rendering
+the site.
+The rendered page can be viewed by opening `localhost:3000` in a browser.
+
 ## To Do
 
 - Test execution _of changed tutorials only_ in CI on PR.