Update screenshots & README

Author: waldbaer

README.md

@@ -27,6 +27,7 @@ Persistent values are typically states, configuration options etc. which shall s
   - Scope and Storage type
 - Node to read and write a concrete persistent value referenced via the config.
 - Configurable `msg` property for input of new persistent value or output of the current value.
+- Configurable `msg` property for output of previous persisted value.
 - Append the current persistent value as object attribute to an configurable `msg` property.
 - Block further flow processing (no output) if the current value matches with a configured rule.
 

doc/images/usage_configuration.png

@@ -133,7 +133,7 @@
 
         // Value config container
         $('#node-config-input-values-container')
-          .css('min-height', '400px')
+          .css('min-height', '150px')
           .css('min-width', '700px')
           .css('padding', '0px')
           .editableList({