update docs to ensure info icon_url will not be used on icon_emoji

Author: DZunke

DependencyInjection/Configuration.php

@@ -63,7 +63,7 @@ private function addIdentities()
             ->children()
                 ->scalarNode('icon_url')
                     ->defaultNull()
-                    ->info('An Url to a specific picture to use as Icon')
+                    ->info('An Url to a specific picture to use as Icon, be sure no emoji is set')
                 ->end()
                 ->scalarNode('icon_emoji')
                     ->defaultNull()

Resources/doc/actions-list.md

@@ -111,7 +111,7 @@ protected $parameter = [
     'identity'     => null,     # Object of Class \DZunke\SlackBundle\Slack\Messaging\Identity
     'channel'      => null,
     'text'         => null,
-    'icon_url'     => null,
+    'icon_url'     => null,     # only one of icon_url or icon_emoji could be used
     'icon_emoji'   => null,
     'parse'        => 'full',
     'link_names'   => 1,