Add help for redirecting password via file

password-change-tool/change-user-password.sh

@@ -22,7 +22,8 @@ cat << HELP
 Script to update the password of a user.
 The password is either
  - entered interactively
- - redirected from STDIN via ${MY_NAME} ... <<< 'newpassword'
+ - redirected from STDIN via    ${MY_NAME} ... <<< 'newpassword'
+ - redirected from a file via   ${MY_NAME} ... < /path/to/file-with-password
 
 Usage: $1 [OPTION]
 Mandatory:
@@ -127,4 +128,4 @@ done
 check_if_root
 check_user
 get_password
-change_user_password
+change_user_password