fix comment

[angrymouse]

Fixed incorrect path in comment for posix.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[aduh95]

Here's the result on my machine:

$ node -p "path.posix.basename('/tmp/myfile.html')"
myfile.html

[aduh95]

@angrymouse Maybe there is a bug on the Node.js version you are using, but the path.posix methods should definitely not return a Windows-like path. If that's what you are seeing on you're machine, you should check to see if you are using an up-to-date version of Node.js, and if you are, fill an issue on this repo so it can be fixed.