minor correction to README.md example

[jnorwood]

just a small thing ... The current cmake build creates bin/nnef-validator, while the README.md example uses bin/nnef-parser.

Example of execution under Linux:

$ cd <NNEF parser build directory>
$ ./bin/nnef-parser ../examples/googlenet_comp.txt --layers
$ ./bin/nnef-parser ../examples/googlenet_flat.txt

jay@JayNorwood /cygdrive/c/nnef/NNEF-Tools/parser/cpp/build $ ls bin/nn* bin/nnef-validator.exe

[gyenesvi]

Right, thanks for spotting that, I corrected the readme.