chore: regenerate README (#532)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-11-20 16:10:37,646 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerydatatransfer/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-11-20 16:10:38,619 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/3fbcc8cc-b3fc-4bcc-9792-e691740002f4/targets

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.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquerydatatransfer.git",
-        "sha": "0f04fa4b8162b41fbb3e3e8164dd881b838c624b"
+        "sha": "caac326028df9ff51e3f68c4159e2fff5828c6cd"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "39b7149da4026765385403632db3c6f63db96b2c"
+        "sha": "68742c6016bf0d16948a572633d17955a8737414"
       }
     }
   ]

README.md

@@ -91,7 +91,10 @@ has instructions for running the samples.
 | Sample                      | Source Code                       | Try it |
 | --------------------------- | --------------------------------- | ------ |
 | Copy Dataset | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CopyDataset.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CopyDataset.java) |
+| Create Ad Manager Transfer | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateAdManagerTransfer.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateAdManagerTransfer.java) |
+| Create Ads Transfer | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateAdsTransfer.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateAdsTransfer.java) |
 | Create Amazon S3 Transfer | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateAmazonS3Transfer.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateAmazonS3Transfer.java) |
+| Create Campaignmanager Transfer | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateCampaignmanagerTransfer.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateCampaignmanagerTransfer.java) |
 | Create Cloud Storage Transfer | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateCloudStorageTransfer.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateCloudStorageTransfer.java) |
 | Create Redshift Transfer | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateRedshiftTransfer.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateRedshiftTransfer.java) |
 | Create Scheduled Query | [source code](https://github.com/googleapis/java-bigquerydatatransfer/blob/master/samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateScheduledQuery.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigquerydatatransfer&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigquerydatatransfer/CreateScheduledQuery.java) |