docs: add link to Lighthouse 3rd party audits page (#176)

Author: coliff

facades.md

@@ -2,10 +2,10 @@
 
 In addition to identifying entities, third-party-web also includes data on entities' _products_, and available alternative libraries for products known as _facades_. A **third-party product** is a third-party resource that is included on a page associated with a specific integration/SDK/API, for example: a YouTube embed iframe. A **facade** is a frontend element which looks similar to the actual product and lazily loads it upon user interaction.  It's expected to be significantly more lightweight/faster. For example: [lite-youtube-embed](https://github.com/paulirish/lite-youtube-embed).
 
-[Lighthouse](https://github.com/GoogleChrome/lighthouse) 7.0 has a new audit that identifies third-party 
-embeds (link coming soon) that can be lazy loaded with a facade. The Lighthouse audit is powered by the facade data in third-party-web.
+[Lighthouse](https://github.com/GoogleChrome/lighthouse) 7.0 has a new audit that [identifies third-party embeds](https://web.dev/third-party-facades/) that can be lazy loaded with a facade. The Lighthouse audit is powered by the facade data in third-party-web.
 
 ## Criteria for adding a new facade
+
 ### Basic functionality
 
 * Loads a frontend "component" which looks like the actual third-party embed.