chore: Update discovery artifacts (#1299)

* chore: update docs/dyn/index.md
* chore(acceleratedmobilepageurl): update the api
* chore(accessapproval): update the api
* chore(accesscontextmanager): update the api
* chore(adexchangebuyer): update the api
* chore(adexchangebuyer2): update the api
* feat(admin): update the api
* feat(admob): update the api
* feat(analyticsadmin): update the api
* chore(analyticsdata): update the api
* chore(androiddeviceprovisioning): update the api
* chore(androidmanagement): update the api
* chore(androidpublisher): update the api
* chore(apigee): update the api
* feat(area120tables): update the api
* chore(assuredworkloads): update the api
* fix(bigquery): update the api
* chore(bigqueryconnection): update the api
* chore(bigquerydatatransfer): update the api
* chore(bigqueryreservation): update the api
* chore(bigtableadmin): update the api
* chore(billingbudgets): update the api
* chore(binaryauthorization): update the api
* chore(blogger): update the api
* chore(books): update the api
* chore(calendar): update the api
* chore(chat): update the api
* chore(chromemanagement): update the api
* chore(chromepolicy): update the api
* chore(chromeuxreport): update the api
* chore(classroom): update the api
* chore(cloudasset): update the api
* chore(cloudbuild): update the api
* chore(cloudchannel): update the api
* chore(clouddebugger): update the api
* chore(clouderrorreporting): update the api
* feat(cloudfunctions): update the api
* chore(cloudiot): update the api
* chore(cloudkms): update the api
* feat(cloudsearch): update the api
* chore(cloudshell): update the api
* chore(cloudtrace): update the api
* chore(composer): update the api
* feat(container): update the api
* feat(containeranalysis): update the api
* chore(content): update the api
* chore(customsearch): update the api
* chore(datacatalog): update the api
* feat(dataflow): update the api
* chore(datalabeling): update the api
* chore(datamigration): update the api
* chore(deploymentmanager): update the api
* feat(dialogflow): update the api
* chore(digitalassetlinks): update the api
* chore(displayvideo): update the api
* chore(dlp): update the api
* chore(dns): update the api
* chore(docs): update the api
* feat(documentai): update the api
* chore(domains): update the api
* chore(domainsrdap): update the api
* chore(doubleclickbidmanager): update the api
* chore(doubleclicksearch): update the api
* chore(drive): update the api
* chore(driveactivity): update the api
* chore(eventarc): update the api
* chore(factchecktools): update the api
* chore(fcm): update the api
* feat(file): update the api
* chore(firebase): update the api
* chore(firebasedatabase): update the api
* chore(firebasedynamiclinks): update the api
* chore(firebasehosting): update the api
* chore(firebaseml): update the api
* chore(fitness): update the api
* chore(games): update the api
* chore(gamesConfiguration): update the api
* chore(gamesManagement): update the api
* chore(gameservices): update the api
* feat(genomics): update the api
* chore(gkehub): update the api
* chore(gmail): update the api
* chore(gmailpostmastertools): update the api
* chore(groupsmigration): update the api
* chore(groupssettings): update the api
* chore(healthcare): update the api
* chore(homegraph): update the api
* chore(iam): update the api
* chore(iamcredentials): update the api
* chore(iap): update the api
* chore(indexing): update the api
* chore(jobs): update the api
* chore(language): update the api
* chore(libraryagent): update the api
* chore(licensing): update the api
* chore(lifesciences): update the api
* chore(localservices): update the api
* chore(logging): update the api
* chore(manufacturers): update the api
* chore(memcache): update the api
* chore(metastore): update the api
* chore(ml): update the api
* chore(monitoring): update the api
* chore(mybusinessaccountmanagement): update the api
* chore(mybusinesslodging): update the api
* feat(networkmanagement): update the api
* chore(notebooks): update the api
* feat(ondemandscanning): update the api
* chore(orgpolicy): update the api
* feat(osconfig): update the api
* chore(oslogin): update the api
* chore(pagespeedonline): update the api
* feat(people): update the api
* chore(playablelocations): update the api
* chore(playcustomapp): update the api
* chore(policysimulator): update the api
* chore(policytroubleshooter): update the api
* chore(prod_tt_sasportal): update the api
* chore(pubsub): update the api
* chore(realtimebidding): update the api
* chore(recommendationengine): update the api
* chore(recommender): update the api
* chore(redis): update the api
* chore(remotebuildexecution): update the api
* chore(reseller): update the api
* chore(retail): update the api
* chore(run): update the api
* chore(runtimeconfig): update the api
* chore(safebrowsing): update the api
* chore(sasportal): update the api
* chore(script): update the api
* chore(searchconsole): update the api
* chore(securitycenter): update the api
* chore(serviceconsumermanagement): update the api
* chore(servicecontrol): update the api
* chore(servicenetworking): update the api
* fix(serviceusage): update the api
* chore(sheets): update the api
* chore(slides): update the api
* chore(smartdevicemanagement): update the api
* chore(spanner): update the api
* chore(speech): update the api
* chore(storage): update the api
* chore(storagetransfer): update the api
* chore(streetviewpublish): update the api
* chore(sts): update the api
* chore(tagmanager): update the api
* chore(tasks): update the api
* chore(testing): update the api
* chore(toolresults): update the api
* chore(tpu): update the api
* chore(trafficdirector): update the api
* chore(transcoder): update the api
* chore(translate): update the api
* chore(vault): update the api
* chore(vectortile): update the api
* chore(vision): update the api
* chore(webrisk): update the api
* feat(websecurityscanner): update the api
* chore(workflowexecutions): update the api
* chore(workflows): update the api
* chore(youtube): update the api
* chore(youtubeAnalytics): update the api
* chore(youtubereporting): update the api
* chore(docs): Add new discovery artifacts and reference documents
diff --git a/googleapiclient/discovery_cache/documents/servicenetworking.v1beta.json b/googleapiclient/discovery_cache/documents/servicenetworking.v1beta.json
index d178976..dce9bba 100644
--- a/googleapiclient/discovery_cache/documents/servicenetworking.v1beta.json
+++ b/googleapiclient/discovery_cache/documents/servicenetworking.v1beta.json
@@ -307,7 +307,7 @@
       }
     }
   },
-  "revision": "20210410",
+  "revision": "20210420",
   "rootUrl": "https://servicenetworking.googleapis.com/",
   "schemas": {
     "AddDnsRecordSetMetadata": {
@@ -502,7 +502,7 @@
       "type": "object"
     },
     "Authentication": {
-      "description": "`Authentication` defines the authentication configuration for an API. Example for an API targeted for external use: name: calendar.googleapis.com authentication: providers: - id: google_calendar_auth jwks_uri: https://www.googleapis.com/oauth2/v1/certs issuer: https://securetoken.google.com rules: - selector: \"*\" requirements: provider_id: google_calendar_auth",
+      "description": "`Authentication` defines the authentication configuration for API methods provided by an API service. Example: name: calendar.googleapis.com authentication: providers: - id: google_calendar_auth jwks_uri: https://www.googleapis.com/oauth2/v1/certs issuer: https://securetoken.google.com rules: - selector: \"*\" requirements: provider_id: google_calendar_auth - selector: google.calendar.Delegate oauth: canonical_scopes: https://www.googleapis.com/auth/calendar.read",
       "id": "Authentication",
       "properties": {
         "providers": {