Update doc for dataToGPU change (#7651)

* Update doc for dataToGPU change

* remove buffer.size

---------

Co-authored-by: Matthew Soulanille <[email protected]>

Author: qjia7

docs/OPTIMIZATION_PURE_GPU_PIPELINE.md

@@ -78,7 +78,6 @@ const uniformBindGroup = device.createBindGroup({
       binding: 1,
       resource: {
         buffer: data.buffer,
-        size: data.bufSize,
       },
     },
     ...