bert-squad: readme file update (#810)

One line change in the readme file for the wrong file name.
Co-authored-by: mvermeulen <5479696+mvermeulen@users.noreply.github.com>

examples/python_bert_squad_example/README.md

@@ -9,7 +9,7 @@ There are two ways to run the example:
 1) Install MIGraphX to your environment. Please follow the steps to build MIGraphX given at https://github.com/ROCmSoftwarePlatform/AMDMIGraphX
 2) Install the requirements file
 ```
-pip3 install -r requirements_migraphx.txt
+pip3 install -r requirements_bertsquad.txt
 ```
 3) Install `unzip` and fetch the uncased file (vocabulary):
 ```