build: run docs regen in synth.py (#1059)

diff --git a/docs/dyn/compute_beta.regionUrlMaps.html b/docs/dyn/compute_beta.regionUrlMaps.html
index 3680b4b..722b85a 100644
--- a/docs/dyn/compute_beta.regionUrlMaps.html
+++ b/docs/dyn/compute_beta.regionUrlMaps.html
@@ -1991,6 +1991,8 @@
     <code class="details" id="invalidateCache">invalidateCache(project, region, urlMap, body=None, requestId=None)</code>
   <pre>Initiates a cache invalidation operation, invalidating the specified path, scoped to the specified UrlMap.
 
+For more information, see [Invalidating cached content](/cdn/docs/invalidating-cached-content).
+
 Args:
   project: string, Project ID for this request. (required)
   region: string, Name of the region scoping this request. (required)