docs: Add CSS selector to interaction config doc(#92)

Author: limhjgrace

docs/cdn_installation.md

@@ -137,7 +137,7 @@ telemetries: [
 
 | Name | Type | Default | Description |
 | --- | --- | --- | --- |
-| events | Array | `[]` | An array of target DOM events to record. <br/><br/>For example, to record a single element with Id `mybutton`, use `[{event: 'click', elementId: 'mybutton' }]`. To record a complete clickstream, use `[{ event: 'click', element: document }]`. |
+| events | Array | `[]` | An array of target DOM events to record. Each DOM event is defined by an *event* and a *selector*. The event must be a [DOM event](https://www.w3schools.com/jsref/dom_obj_event.asp). The selector must be one of (1) `cssLocator`, (2) `elementId` or (3) `element`.<br/><br/>When two or more selectors are provided for a target DOM event, only one selector will be used. The selectors will be honored with the following precedence: (1) `cssLocator`, (2) `elementId` or (3) `element`. For example, if both `cssLocator` and `elementId` are provided, only the `cssLocator` selector will be used.<br/><br/>**Examples:**<br/>Record all elements identified by CSS selector `[label="label1"]`:<br/> `[{ event: 'click', cssLocator: '[label="label1"]'`<br/><br/>Record a single element with ID `mybutton`:<br/>`[{ event: 'click', elementId: 'mybutton' }]`<br/><br/>Record a complete clickstream<br/>`[{ event: 'click', element: document }]`. |
 
 ## Performance