chore: regenerate README (#818)

This PR was generated using Autosynth. 🌈


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

```
2020-10-16 18:50:48,612 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquery/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-16 18:50:49,633 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/ddf6b66a-2ca8-4e96-9a24-4e8b6454ff0f/targets

- [ ] To automatically regenerate this PR, check this box.

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquery.git",
-        "sha": "71e7d4804e1facfb921892dc702adaec35e47cd0"
+        "sha": "8082ff231001c76f97077df25308859c5dfbfc80"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "3c1fd09ba8d1c7b7092662f6f8330f521d4e7739"
+        "sha": "da5c6050d13b4950c82666a81d8acd25157664ae"
       }
     }
   ]

README.md

@@ -19,7 +19,7 @@ See https://github.com/GoogleCloudPlatform/cloud-opensource-java/wiki/The-Google
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>11.1.0</version>
+      <version>12.1.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -40,7 +40,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-bigquery</artifactId>
-  <version>1.120.0</version>
+  <version>1.122.2</version>
 </dependency>
 
 ```