Add grid definition to Quick Start (#116)

Co-authored-by: Sudhakar Mahalingam <76498452+likian24@users.noreply.github.com>

Author: dearmachi

README.md

@@ -40,10 +40,14 @@ end
 # Launch
 vector_size = 2^20
 tile_size = 16
+
+blocks = cld(vector_size, tile_size)
+grid = (blocks, 1, 1)       
+
 a, b = CUDA.rand(Float32, vector_size), CUDA.rand(Float32, vector_size)
 c = CUDA.zeros(Float32, vector_size)
 
-ct.launch(vadd, (cld(vector_size, tile_size), 1, 1), a, b, c, ct.Constant(tile_size))
+ct.launch(vadd, grid, a, b, c, ct.Constant(tile_size))
 
 @assert c == a .+ b
 ```