Update buildwithcmake.rst

Author: zhi-wang

doc/manual/m/install/buildwithcmake.rst

@@ -10,7 +10,7 @@ an example to compile the GPU code without OpenACC:
 .. code-block:: bash
 
    cd tinker9 && mkdir build
-   FC=gfortran compute_capability=70 gpu_lang= cmake ..
+   FC=gfortran compute_capability=70 gpu_lang=CUDA cmake ..
    make
    make test