Improve examples README.

- Wrap overlong lines.
- Add `i128_demo`.
- Fix the link to `path_tracer`.

Author: nnethercote

examples/README.md

@@ -1,23 +1,36 @@
 # CUDA + Rust examples
 
-The examples in here showcase both the GPU side and the CPU side of writing a tool which uses the GPU.
+The examples in here showcase both the GPU side and the CPU side of writing a tool which uses the
+GPU.
 
 ## Available Examples
 
 ### [vecadd](vecadd)
+
 A simple vector addition example demonstrating basic CUDA kernel usage.
 
 ### [gemm](gemm)
+
 General Matrix Multiplication (GEMM) implementation showing more complex CUDA operations.
 
+### [i128_demo](i128_demo)
+
+A simple demo that uses 128-bit integer operations.
+
 ### [sha2_crates_io](sha2_crates_io)
-Demonstrates using an existing Rust crate ([`sha2`](https://crates.io/crates/sha2) from crates.io) on both CPU and GPU without modification. Shows that the same cryptographic hashing code can run on CUDA, producing identical results to the CPU implementation.
 
-### [Interactive Path Tracer](path_tracer)
-A very simple interactive Path Tracer inspired by [Ray Tracing In One Weekend](https://raytracing.github.io/books/RayTracingInOneWeekend.html)
-which runs on CPU or GPU, with the additional option of running OptiX denoising.
+Demonstrates using an existing Rust crate ([`sha2`](https://crates.io/crates/sha2) from crates.io)
+on both CPU and GPU without modification. Shows that the same cryptographic hashing code can run on
+CUDA, producing identical results to the CPU implementation.
+
+### [Interactive Path Tracer](../crates/optix/examples/path_tracer/)
+
+A very simple interactive Path Tracer inspired by [Ray Tracing In One
+Weekend](https://raytracing.github.io/books/RayTracingInOneWeekend.html) which runs on CPU or GPU,
+with the additional option of running OptiX denoising.
 
 ![Path Tracer](assets/path_tracer.png)
 
-The Path Tracer uses cuda_builder to compile the core path tracer for the GPU and GPU (hardware raytracing), and uses the core path tracer as a normal crate
-for CPU rendering and sharing structures.
+The Path Tracer uses `cuda_builder` to compile the core path tracer for the GPU and GPU (hardware
+raytracing), and uses the core path tracer as a normal crate for CPU rendering and sharing
+structures.