Implement global apt preferences opt

  * Misc: fix 'humanname' processing
  * require salt-formula-salt=0.4+201812211629.9b3097a or higer
    - add dep. salt

Prod-relate: PROD-25786 (PROD:25786)

Change-Id: Ie93425d579a44e1a9775a37e9592530c1e0be02c
diff --git a/README.rst b/README.rst
index ef99718..cdbfeae 100644
--- a/README.rst
+++ b/README.rst
@@ -956,6 +956,27 @@
                priority: 900
                package: '*'
 
+Sometimes better to use one pining rule file, to decrease mistaken
+ordering. You can use those option ``system:apt:preferences``, which would add opts into
+``/etc/apt/preferences`` file:
+
+.. code-block:: yaml
+
+  parameters:
+    linux:
+      system:
+        apt:
+          preferences:
+            enabled: true
+            rules:
+              100:
+                enabled: true
+                name: 'some origin pin'
+                pin: 'release o=Debian'
+                priority: 1100
+                package: '*'
+
+
 If you need to add multiple pin rules for one repo, please use new,ordered definition format
 ('pinning' definition will be in priotity to use):