Website: add NSpecRunner local path

[BrainCrumbz]

In index.md, where it says:

---

• Then run the tests using NSpecRunner.exe:

>NSpecRunner.exe YourClassLibraryName\bin\debug\YourClassLibraryName.dll
my first spec
  asserts at the method level
  describe nesting
    asserts in a method
    more nesting
      also asserts in a lambda

---

we should specify where that executable is to be found. It should be something like:

<path to solution>\packages\<nspec package>\tools\net452\NSpecRunner.exe

[amirrajan]

The package manager console automatically loads that path. It probably is worth stating either way (can't be too explicit).

[BrainCrumbz]

Well said, didn't thought about that. First assumption was "that is a windows command prompt". Then it might be enough to start prompt with PM> and yes, anyway, mention that if not from Package Manager console, the path should be added.

[BrainCrumbz]

#166 also introduced PM> prompt, so that is sorted. For one thing though, the console does not load that, at least on Windows Visual Studio 2015, with a .NET Core project targeting both .NET Core and .NET Framework.

Maybe that works with a .NET Framework project?