chore: regenerate README (#155)

This PR was generated using Autosynth. 🌈


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

```
2020-10-06 22:16:00,215 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigqueryconnection/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-06 22:16:01,194 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/8408a3d5-1a03-44e3-ad1d-ebea7b956240/targets

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

@@ -0,0 +1,18 @@
+{
+  "sources": [
+    {
+      "git": {
+        "name": ".",
+        "remote": "https://github.com/googleapis/java-bigqueryconnection.git",
+        "sha": "365d497e8587412e6c1f50bd5e53f8257e77e213"
+      }
+    },
+    {
+      "git": {
+        "name": "synthtool",
+        "remote": "https://github.com/googleapis/synthtool.git",
+        "sha": "487eba79f8260e34205d8ceb1ebcc65685085e19"
+      }
+    }
+  ]
+}

README.md

@@ -75,6 +75,8 @@ has instructions for running the samples.
 
 | Sample                      | Source Code                       | Try it |
 | --------------------------- | --------------------------------- | ------ |
+| Create Connection | [source code](https://github.com/googleapis/java-bigqueryconnection/blob/master/samples/snippets/src/main/java/com/example/bigqueryconnection/CreateConnection.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigqueryconnection&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigqueryconnection/CreateConnection.java) |
+| Delete Connection | [source code](https://github.com/googleapis/java-bigqueryconnection/blob/master/samples/snippets/src/main/java/com/example/bigqueryconnection/DeleteConnection.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigqueryconnection&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigqueryconnection/DeleteConnection.java) |
 | Quickstart Sample | [source code](https://github.com/googleapis/java-bigqueryconnection/blob/master/samples/snippets/src/main/java/com/example/bigqueryconnection/QuickstartSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigqueryconnection&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigqueryconnection/QuickstartSample.java) |