Added the .gitignore file.

[this-is-batman]

• This will help in keeping the working tree clean.
• All the .bin files and the /data/ folder have been added to gitignore.

[this-is-batman]

Fixes https://github.com/karpathy/llm.c/issues/43

[this-is-batman]

Athough I realise this is not a necessary thing to do, and we can mostly ignore this, it helps in keeping a clean working directory. I have tried to keep only the basic things in the .gitignore file.

[davmacario]

What do you think about adding entries for commonly ignored files? Something along the lines of this.

[this-is-batman]

What do you think about adding entries for commonly ignored files? Something along the lines of this.

This looks good, but I prefer to keep a small gitignore file, and improve upon it as the project matures.