chore: move async_api example to the samples/introduction/ subdirectory

Author: madhav-madhusoodanan

Cargo.toml

@@ -8,8 +8,6 @@ members = [
 
   "xtask",
 
-  "examples/cuda/async_api",
-  "examples/cuda/async_api/kernels",
   "examples/cuda/vecadd",
   "examples/cuda/vecadd/kernels",
   "examples/cuda/gemm",
@@ -22,6 +20,9 @@ members = [
   "examples/optix/*",
   "tests/compiletests",
   "tests/compiletests/deps-helper",
+
+  "samples/introduction/async_api",
+  "samples/introduction/async_api/kernels",
 ]
 
 exclude = [

examples/cuda/async_api/Cargo.toml renamed to samples/introduction/async_api/Cargo.toml

@@ -38,7 +38,6 @@ fn main() -> Result<(), cust::error::CudaError> {
     let stream = Stream::new(StreamFlags::NON_BLOCKING, None).expect("Stream couldn't be init!");
 
     const N: usize = 16 * 1024 * 1024;
-    const N_BYTES: usize = N * (i32::BITS as usize);
     let value = 26;
 
     let blocks = BlockSize::xy(512, 1);