MINOR: [Docs] Remove extra line in README.md (fix pre-commit)

[axreldable]

What's Changed

Remove extra line in README.md for fixing the end-of-file-fixer hook in the pre-commit build.

E.g. here in the main branch build.

fix end of files.........................................................Failed
- hook id: end-of-file-fixer
- exit code: 1
- files were modified by this hook

Fixing README.md

[axreldable]

Please add documentation.