chore: regenerate README (#322)

This PR was generated using Autosynth. 🌈


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

```
2020-12-14 19:16:56,263 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-container/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2020-12-14 19:16:57,234 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/9d5bd8a5-e0ca-4fee-8985-59a99785bee0/targets

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

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-container.git",
-        "sha": "fe779ca632474a60ed43980b86ffb5a2d33f1fb4"
+        "sha": "263b240bb6cad0bcb99e5c30e045c71b31f6d9ee"
       }
     },
     {

README.md

@@ -38,7 +38,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-container</artifactId>
-  <version>1.2.0</version>
+  <version>1.2.1</version>
 </dependency>
 
 ```