chore: regenerate README (#531)

This PR was generated using Autosynth. 🌈


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

```
2021-05-18 07:20:18,691 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-logging/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-05-18 07:20:19,999 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/2d4753b2-ff85-43e3-a098-346b2ef4b829/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-logging.git",
-        "sha": "9d6b783cd2eecfb702978856ffe7cc3b40a63bc9"
+        "sha": "2853f13e5c91cb3841606fc6059a982e9610bef8"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "4f4b1b9b8d8b52f1e9e4a76165896debce5ab7f1"
+        "sha": "c86c7a60985644eab557949363a38301d40d78d2"
       }
     }
   ]

README.md

@@ -39,7 +39,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-logging</artifactId>
-  <version>2.2.2</version>
+  <version>2.2.3</version>
 </dependency>
 
 ```