Build instructions clarification in docs

[newling]

The instructions in https://xilinx.github.io/mlir-air/building.html appear to have a typo:

git clone https://github.com/stephenneuendorffer/aie-rt
cd aie-rt
git checkout phoenix_v2023.2
cd driver/src
make -f Makefile.Linux CFLAGS="-D__AIEAMDAIR__"
sudo cp -r ../include /opt/aiengine/
sudo cp libxaiengine.so* /opt/xaiengine/lib/
export LD_LIBRARY_PATH=/opt/xaiengine/lib:${LD_LIBRARY_PATH}

opt/aiengine vs opt/xaiengine ?