update readme

README.md

@@ -290,6 +290,7 @@ var styles = StyleSheet.create({
 ```
 
 ### Configurable props
+* [adTagUrl](#adTagUrl)
 * [allowsExternalPlayback](#allowsexternalplayback)
 * [audioOnly](#audioonly)
 * [automaticallyWaitsToMinimizeStalling](#automaticallyWaitsToMinimizeStalling)
@@ -356,6 +357,21 @@ var styles = StyleSheet.create({
 
 ### Configurable props
 
+#### adTagUrl
+Sets the ad url
+
+Example: 
+```
+const adTagUrl = "https://pubads.g.doubleclick.net/gampad/ads?sz=640x480&iu=/124319096/external/"
++ "ad_rule_samples&ciu_szs=300x250&ad_rule=1&impl=s&gdfp_req=1&env=vp"
++ "&output=vmap&unviewed_position_start=1&cust_params=deployment%3Ddevsite"
++ "%26sample_ar%3Dpremidpost&cmsid=496&vid=short_onecue&correlator=";
+
+adTagUrl={adTagUrl}
+```
+
+Platforms: all
+
 #### allowsExternalPlayback
 Indicates whether the player allows switching to external playback mode such as AirPlay or HDMI.
 * **true (default)** - allow switching to external playback mode