added example

README.md

@@ -2,6 +2,27 @@
 
 A Rust Cargo crate for finding the distance between a point and a constructive solid geometry (CSG) surface
 
+## Example usage
+
+This example finds the distance from a point along a vector to a spherical surface.
+
+```rust
+use csg_distance::{Point, Vector, CSGSurface};
+
+fn main() {
+    let point = Point { x: 1.0, y: 2.0, z: 3.0 };
+    let vector = Vector { dx: 1.0, dy: 0.0, dz: 0.0 };
+
+    let surface = CSGSurface::Sphere { x: 0.0, y: 0.0, z: 0.0, radius: 1.0 };
+
+    if let Some(distance) = surface.distance_to_surface(&point, &vector) {
+        println!("Distance to surface: {}", distance);
+    } else {
+        println!("No intersection with the surface.");
+    }
+}
+```
+
 ## Supported Surfaces
 
 csg_surface_distance supports the following types of surfaces: