docs: Add `-o` to unzip in linux install one-liner

This will overwrite any existing `trash.zip` file, which is useful if
the user is upgrading and the `trash` executable is already there.

README.md

@@ -56,7 +56,7 @@ too. Run this from the directory where you want `trash` to be installed.
 
 ```bash
  wget -O trash.zip https://github.com/rcdailey/trash-updater/releases/latest/download/trash-linux-x64.zip \
-    && unzip trash.zip && rm trash.zip && chmod +x trash
+    && unzip -o trash.zip && rm trash.zip && chmod +x trash
 ```
 
 ## Getting Started