salt layer: add yaml layer dependency

contrib/!config/salt/README.org

@@ -1,20 +1,17 @@
 #+TITLE: Saltstack contribution layer for Spacemacs
 
 [[file:img/saltstack.png]]
+
 * Table of Contents                                                   :TOC@4:
  - [[#description][Description]]
  - [[#install][Install]]
 
 * Description
-
 This layer provides syntax highlighting for Saltstack files.
 
 * Install
-
 To use this contribution add it to your =~/.spacemacs=
 
 #+BEGIN_SRC emacs-lisp
-  (setq-default dotspacemacs-configuration-layers '(salt yaml))
+  (setq-default dotspacemacs-configuration-layers '(salt))
 #+END_SRC
-
-Note that this layer requires the yaml layer.

contrib/!config/salt/config.el

@@ -0,0 +1,14 @@
+;;; config.el --- salt Layer packages File for Spacemacs
+;;
+;; Copyright (c) 2012-2015 Sylvain Benner
+;; Copyright (c) 2014-2015 Sylvain Benner & Contributors
+;;
+;; Author: Sylvain Benner <sylvain.benner@gmail.com>
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+;; Prerequisites
+
+(configuration-layer/declare-layer 'yaml)