add --prerelease

src/config.rs

@@ -44,6 +44,7 @@ pub fn save_value(config_path: PathBuf, key: &str, value: bool) {
         "force_update" => config.force_update = value,
         "use_https" => config.use_https = value,
         "skip_redist" => config.skip_redist = value,
+        "prerelease" => config.prerelease = value,
         _ => (),
     }
     save(config_path, config);