update readme organization

Author: jacklowrie

README.md

@@ -19,8 +19,6 @@ Fall 2024.
 
 `uv add chordnet`
 
-## Development
-See `CONTRIBUTING.md`.
 
 ## Usage
 to stay consistent with the language from the original paper, we recommend
@@ -36,3 +34,10 @@ ring.leave()
 ```
 This fits with the concept of "joining" an existing ring network, or creating a
 new one. Examples follow this practice.
+
+## Development
+See `CONTRIBUTING.md`.
+
+## Security
+If you discover a security issue, **please do not open a public issue**.
+See `SECURITY.md` for the full policy/reporting instructions.