new shebangs

README.md

@@ -30,7 +30,7 @@ cd my-env && make
 1. Create a new shell script in `./install`, `./upgrade` or `./uninstall` directory.  
    At the beggining of a file you must write these two lines:
    ```shell
-   #!/bin/bash
+   #!/usr/bin/env bash
    ##makedesc: Your description for Makefile
    ```
 2. Make this script executable, e.g.: