fix: use DUFS_CONFIG to specify the config file path (#286)

README.md

@@ -333,6 +333,7 @@ All options can be set using environment variables prefixed with `DUFS_`.
 
 ```
   [serve-path]                DUFS_SERVE_PATH=/dir
+      --config <path>         DUFS_CONFIG=config.yaml
   -b, --bind <addrs>          DUFS_BIND=0.0.0.0
   -p, --port <port>           DUFS_PORT=5000
       --path-prefix <path>    DUFS_PATH_PREFIX=/path

src/args.rs

@@ -29,7 +29,7 @@ pub fn build_cli() -> Command {
         )
         .arg(
             Arg::new("config")
-                .env("DUFS_SERVE_PATH")
+                .env("DUFS_CONFIG")
 				.hide_env(true)
                 .short('c')
                 .long("config")