chore: regenerate README (#314)

This PR was generated using Autosynth. 🌈


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

```
2021-06-17 16:30:16,702 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-mediatranslation/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-17 16:30:18,007 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/0cd7fb9e-3b13-45d5-b375-695ea3f8bfcb/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-mediatranslation.git",
-        "sha": "f0299cd750e3869cbcd1bab3a77c140ccf8647d9"
+        "sha": "15d7afa53871204d8731abbc45a6b7b7db4a5f5f"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "2430f8d90ed8a508e8422a3a7191e656d5a6bf53"
+        "sha": "aed1f0344811f13561df6a73de82552c6e6df24e"
       }
     }
   ]

README.md

@@ -20,7 +20,7 @@ If you are using Maven, add this to your pom.xml file:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-mediatranslation</artifactId>
-  <version>0.5.0</version>
+  <version>0.5.1</version>
 </dependency>
 
 ```