`df` written in Rust

Introduction

I created this repo to learn Rust programming.

Implementation Table(compared to df in coreutils)

options	✔️ ?
`-a`	✔️
`-B`
`-h`	✔️
`-H`	✔️
`-i`	✔️
`-k`
`-l`	✔️
`--no-sync`
`--output`	✔️
`-P`
`--sync`
`--total`
`-t`	✔️
`-x`	✔️