GhidraProject: fix root path in docs

[gemesa]

While following the GhidraProject openProgram API docs, I got this error when trying to call openProgram on Windows like this:

program = project.openProgram("\\", domainFile.getName(), true)

java.lang.IllegalArgumentException: Absolute path must begin with '/'
        at ghidra.framework.data.DefaultProjectData.getFile(DefaultProjectData.java:663)
        at ghidra.base.project.GhidraProject.openProgram(GhidraProject.java:303)

So turns out it should be "/" under both Linux and Windows. I also tested it in both cases and it works.

[ryanmkurtz]

That is a project path, which is OS-indepenent and always uses the forward-slash notation. The javadoc is just wrong...i'll fix it, thanks!

[ryanmkurtz]

Oops, i didn't realize this was a PR so i fixed it myself.

[gemesa]

Not a problem at all.