📖 Update documentation for amp-consent integration in ad (#15493)

* Update ad consent doc.

* nit

* update

ads/README.md

@@ -220,10 +220,11 @@ Note that if the creative needs to resize on user interaction, the creative can
 ### amp-consent integration
 If [amp-consent](https://github.com/ampproject/amphtml/blob/master/extensions/amp-consent/amp-consent.md) extension is used on the page, `data-block-on-consent` attribute
 can be added to `amp-ad` element to respect the corresponding `amp-consent` policy.
-In that case, the `amp-ad` element will be blocked for loading until the consent
-responded. Once `amp-ad` is unblocked, 3rd party ad scripts can access the consent
-related information via the following
-`window.context` APIs.
+In that case, the `amp-ad` element will be blocked from loading until the consent accepted.
+Individual ad network can override this default consent handling by putting a `consentHandlingOverride: true` in `ads/_config.js`.
+Doing so will unblock the ad loading once the consent is responded. It will be then the ad network's responsibility
+to respect user's consent choice, for example to serve non-personalized ads on consent rejection.
+AMP runtime provides the following `window.context` APIs for ad network to access the consent state.
 
 <dl>
   <dt><code>window.context.initialConsentState</code></dt>
@@ -244,6 +245,9 @@ related information via the following
   </dd>
 </dl>
 
+After overriding the default consent handling behavior, don't forget to update your publisher facing
+ documentation with the new behaviors on user's consent choices.
+
 ### Optimizing ad performance
 
 #### JS reuse across iframes