update docs addMarker

src/edit_session.js

@@ -540,7 +540,7 @@ class EditSession {
      * Adds a new marker to the given `Range`. If `inFront` is `true`, a front marker is defined, and the `'changeFrontMarker'` event fires; otherwise, the `'changeBackMarker'` event fires.
      * @param {Range} range Define the range of the marker
      * @param {String} clazz Set the CSS class for the marker
-     * @param {Function | String} type Identify the type of the marker
+     * @param {Function | String} type Identify the renderer type of the marker. If string provided, corresponding built-in renderer is used. Supported string types are "fullLine", "screenLine", "text" or "line". If a Function is provided, that Function is used as renderer.
      * @param {Boolean} inFront Set to `true` to establish a front marker
      *
      * @return {Number} The new marker id