Update usage

Directory not preceded by `-d` is no longer valid.

Author: spenserblack

README.md

@@ -23,7 +23,7 @@ Clone the repository and install to `/usr/local/bin` with `make install`.
 Or get the binary from [here](https://github.com/o2sh/onefetch/releases) and add it to your $PATH.
 
 ```sh
-$ onefetch /path/of/your/repo
+$ onefetch -d /path/of/your/repo
  ```
  Or