Add usage instructions to README.

README.md

@@ -4,6 +4,14 @@
 
 ooru.space is an open-source, open-data directory of public community and "third" spaces across India. Visit it at https://ooru.space
 
+## Usage
+
+The site is a [Zola](https://getzola.org) static site.
+
+- Run `python scripts/generate_site.py data/entries.yml ./content/spaces/` to generate Zola content files for all entries.
+- Run `zola serve` (to preview) or `zola build` to generate the full static site.
+
+
 ## License
 - The data (`data/entries.yml` and its CSV form published on the website) are licensed under CC BY-SA 4 (Creative Commons Attribution-ShareAlike 4.0)
 - The repository (excluding data) and all the code in it is licensed under the MIT License