message: shaders: fix setting name in README.md
  Example shows attribute `experimental.pixelShaderEffect`, should be `experimental.pixelShaderPath`
diff: @@ -49,7 +49,7 @@ float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
  Save this file as `C:\temp\invert.hlsl`, then update a profile with the setting:
  ```
  -"experimental.pixelShaderEffect": "C:\\temp\\invert.hlsl"
  +"experimental.pixelShaderPath": "C:\\temp\\invert.hlsl"
  ```
  Once the settings file is saved, open a terminal with the changed profile. It should now invert the colors of the screen!
  