Misleading information in the readme

[fishermedders]

Since this project is ever-evolving, I figured that I'd pitch my two cents, so here goes.

When I was attempting to use TNT, the readme states that the anvil world and the .tnt file are to be named the same thing when converting an anvil world to TNT. I believe this to be misleading, as when you attempt this in practice, the it attempts to load the world (which would be an empty file), and throws an ArrayIndexOutOfBoundsException, which is the expected behavior (the file is empty, but exists, just no world to load from the .tnt file). It should be said in this area that on conversion, the .tnt file should not exist yet.

The reason I didn't submit a PR and chose issues instead was that I didn't want to decide the wording of the readme or the behavior of the library for you guys, but at the same time wanted to help out others who may stumble upon this in the future.

Also, yes, hindsight is 20/20 and this should have been obvious to me 😛