Update README copyright notice to 2019 (#8606)

vilhelmprytz · paramat · commit cf9108433c21 · 2019-06-19T01:09:16.000+01:00
diff --git a/README.md b/README.md
@@ -7,7 +7,7 @@ Minetest
 
 Minetest is a free open-source voxel game engine with easy modding and game creation.
 
-Copyright (C) 2010-2018 Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2010-2019 Perttu Ahola <celeron55@gmail.com>
 and contributors (see source file comments and the version control log)
 
 In case you downloaded the source code:
