update readme

README.md

@@ -8,7 +8,7 @@
 
 __v1.+ requires `markdown-it` v4.+, see changelog.__
 
-`${image?fileName=joy%2Epng&align=None}` => `<span id="widget-11455839862556-795655980" class="widgetContainer" widgetparams="image?fileName=joy%2Epng&amp;align=None" />`
+`${image?fileName=joy%2Epng&align=None}` => `<span id="widget-0my-unique-div-id" class="widgetContainer" widgetparams="image?fileName=joy%2Epng&amp;align=None" />`
 
 
 ## Install
@@ -26,10 +26,12 @@ bower install markdown-it-synapse --save
 var md = require('markdown-it')()
             .use(require('markdown-it-synapse'));
 
-md.render('${image?fileName=joy%2Epng&align=None}') // => '<span id="widget-11455839862556-795655980" class="widgetContainer" widgetparams="image?fileName=joy%2Epng&amp;align=None" />'
+md.render('${image?fileName=joy%2Epng&align=None}', 'my-unique-div-id') // => '<span id="widget-0my-unique-div-id" class="widgetContainer" widgetparams="image?fileName=joy%2Epng&amp;align=None" />'
 
 ```
 
+The widgetparams can be used to determine what kind of html widget should be rendered in the output container.
+
 _Differences in browser._ If you load script directly into the page, without
 package system, module will add itself globally as `window.markdownitSynapse`.