Arm backend: add new cmake line to vgf tutorial (#14938)

Missed updating docs in #14885

cc @freddan80 @per @zingo @oscarandersson8218 @digantdesai

Signed-off-by: Erik Lundell <[email protected]>
Co-authored-by: Erik Lundell <[email protected]>

Author: pytorchbot

docs/source/tutorial-arm-vgf.md

@@ -171,6 +171,7 @@ cmake \
   -DCMAKE_BUILD_TYPE=Debug \
   -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
   -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
+  -DEXECUTORCH_BUILD_EXTENSION_NAMED_DATA_MAP=ON \
   -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
   -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
   -DEXECUTORCH_BUILD_KERNELS_QUANTIZED=ON \