Translate https://github.com/jpenilla/run-paper/wiki/Extensions to Potato

[ryantheleach]

I'm trying to debug https://github.com/oddlama/vane and contribute, but I'm pretty potato when it comes to gradle.

It would be very appreciated if https://github.com/jpenilla/run-paper/wiki/Extensions had a little more information that could be followed for multi-module projects :-), or maybe an example.

[ryantheleach]

For Vane, the following is what would have helped me <3

subprojects { //Note! You may need to ignore non-plugin subprojects here.
    rootProject.tasks.runMojangMappedServer {
        pluginJars(tasks.named<io.papermc.paperweight.tasks.RemapJar>("reobfJar").flatMap { it.inputJar })
    }

    rootProject.tasks.runServer {
        pluginJars(tasks.named<io.papermc.paperweight.tasks.RemapJar>("reobfJar").flatMap { it.outputJar })
    }
}