feat: move examples out

examples/vadd/main.cpp

@@ -0,0 +1,9 @@
+#include <sycl/sycl.hpp>
+
+extern "C" SYCL_EXTERNAL
+void vector_add(double* a, double* b) {
+    auto item = sycl::ext::oneapi::this_work_item::get_nd_item<1>();
+    int idx = item.get_global_id(0);
+
+    a[idx] += b[idx];
+}