Change contributing guidelines to "open open source" based on maxogden/voxel-engine
Change contributing guidelines to "open open source" based on maxogden/voxel-engine

https://github.com/maxogden/voxel-engine/blob/master/contributing.md

GreenBeard/GlowstonePlusPlus,jimmikaelkael/GlowstonePlusPlus,LukBukkit/GlowstonePlusPlus,GreenBeard/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,LukBukkit/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,GreenBeard/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,jimmikaelkael/GlowstonePlusPlus,keke142/GlowstonePlusPlus,Postremus/GlowstonePlusPlus,keke142/GlowstonePlusPlus,BlazePowered/Blaze-Server,LukBukkit/GlowstonePlusPlus,jimmikaelkael/GlowstonePlusPlus,BlazePowered/Blaze-Server,LukBukkit/GlowstonePlusPlus,BlazePowered/Blaze-Server,jimmikaelkael/GlowstonePlusPlus,GreenBeard/GlowstonePlusPlus,Postremus/GlowstonePlusPlus,BlazePowered/Blaze-Server,keke142/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,Postremus/GlowstonePlusPlus,keke142/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,Postremus/GlowstonePlusPlus