chore: Update discovery artifacts (#1336)

## Deleted keys were detected in the following stable discovery artifacts:
servicemanagementv1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/6e593517543990b40c8c6a4c2512e176a0b896f4)

## Discovery Artifact Change Summary:
contentv21[ [More details]](https://github.com/googleapis/google-api-python-client/commit/e18a707b3351372b6bad9961a3cc0a1087fb907b)
dnsv1beta2[ [More details]](https://github.com/googleapis/google-api-python-client/commit/bb15dc54f5f110036bdb96d247d20f6908324547)
servicemanagementv1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/6e593517543990b40c8c6a4c2512e176a0b896f4)
translatev3beta1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/0ab9156b06cbc33b173851b20ab73bdd06522fe8)

chore(acceleratedmobilepageurl): update the api
chore(accessapproval): update the api
chore(adexchangebuyer): update the api
chore(adexchangebuyer2): update the api
chore(admob): update the api
chore(analyticsadmin): update the api
chore(analyticsdata): update the api
chore(analyticsreporting): update the api
chore(androiddeviceprovisioning): update the api
chore(androidmanagement): update the api
chore(apigateway): update the api
chore(apikeys): update the api
chore(area120tables): update the api
chore(calendar): update the api
chore(chromemanagement): update the api
chore(chromepolicy): update the api
chore(cloudchannel): update the api
chore(cloudkms): update the api
chore(cloudtasks): update the api
chore(composer): update the api
feat(content): update the api
chore(customsearch): update the api
chore(datastore): update the api
chore(dialogflow): update the api
chore(digitalassetlinks): update the api
feat(dns): update the api
chore(docs): update the api
chore(domainsrdap): update the api
chore(essentialcontacts): update the api
chore(eventarc): update the api
chore(factchecktools): update the api
chore(file): update the api
chore(firebase): update the api
chore(firebasedatabase): update the api
chore(firestore): update the api
chore(gmailpostmastertools): update the api
chore(indexing): update the api
chore(jobs): update the api
chore(libraryagent): update the api
chore(licensing): update the api
chore(manufacturers): update the api
chore(mybusinessaccountmanagement): update the api
chore(mybusinesslodging): update the api
chore(mybusinessplaceactions): update the api
chore(orgpolicy): update the api
chore(pagespeedonline): update the api
chore(paymentsresellersubscription): update the api
chore(policytroubleshooter): update the api
chore(prod_tt_sasportal): update the api
chore(realtimebidding): update the api
chore(runtimeconfig): update the api
chore(safebrowsing): update the api
chore(script): update the api
chore(serviceconsumermanagement): update the api
feat(servicemanagement): update the api
chore(serviceusage): update the api
chore(slides): update the api
chore(storage): update the api
chore(streetviewpublish): update the api
chore(tasks): update the api
chore(toolresults): update the api
feat(translate): 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/calendar.v3.json b/googleapiclient/discovery_cache/documents/calendar.v3.json
index 9c2f827..9aedeb2 100644
--- a/googleapiclient/discovery_cache/documents/calendar.v3.json
+++ b/googleapiclient/discovery_cache/documents/calendar.v3.json
@@ -1723,7 +1723,7 @@
       }
     }
   },
-  "revision": "20210424",
+  "revision": "20210429",
   "rootUrl": "https://www.googleapis.com/",
   "schemas": {
     "Acl": {
@@ -2104,7 +2104,7 @@
       "id": "ConferenceData",
       "properties": {
         "conferenceId": {
-          "description": "The ID of the conference.\nCan be used by developers to keep track of conferences, should not be displayed to users.\nValues for solution types:  \n- \"eventHangout\": unset.\n- \"eventNamedHangout\": the name of the Hangout.\n- \"hangoutsMeet\": the 10-letter meeting code, for example \"aaa-bbbb-ccc\".\n- \"addOn\": defined by 3P conference provider.  Optional.",
+          "description": "The ID of the conference.\nCan be used by developers to keep track of conferences, should not be displayed to users.\nThe ID value is formed differently for each conference solution type: `\n- eventHangout: ID is not set.\n- eventNamedHangout: ID is the name of the Hangout.\n- hangoutsMeet: ID is the 10-letter meeting code, for example aaa-bbbb-ccc.\n- addOn: ID is defined by the third-party provider.  Optional.",
           "type": "string"
         },
         "conferenceSolution": {