chore: update readme for new option

README.md

@@ -67,7 +67,8 @@ Options:
   --silent                            Ignore any env-cmd errors and only fail on executed program failure.
   --use-shell                         Execute the command in a new shell with the given environment
   --verbose                           Print helpful debugging information
-  -x, --expand-envs                   Replace $var in args and command with environment variables
+  -x, --expand-envs                   Replace $var and ${var} in args and command with environment variables
+  --recursive                         Replace $var and ${var} in env file with the referenced environment variable
   -h, --help                          output usage information
 ```
 
@@ -130,14 +131,14 @@ commands together that share the same environment variables.
 ```
 
 ### Asynchronous env file support
-   
+
    EnvCmd supports reading from asynchronous `.env` files. Instead of using a `.env` file, pass in a `.js`
    file that exports either an object or a `Promise` resolving to an object (`{ ENV_VAR_NAME: value, ... }`). Asynchronous `.rc`
    files are also supported using `.js` file extension and resolving to an object with top level environment
    names (`{ production: { ENV_VAR_NAME: value, ... } }`).
-   
+
    **Terminal**
-   
+
    ```sh
    ./node_modules/.bin/env-cmd -f ./async-file.js node index.js
    ```