Support coloring entire message with the user color (#193)

docs/iamb.5.md

@@ -82,6 +82,9 @@ overridden as described in *PROFILES*.
 **default_room** (type: string)
 > The room to show by default instead of a welcome-screen.
 
+**message_user_color** (type: boolean)
+> Defines whether or not the message body is colored like the username.
+
 **image_preview** (type: image_preview object)
 > Enable image previews and configure it. An empty object will enable the
 > feature with default settings, omitting it will disable the feature.