chore: regenerate README (#475)

This PR was generated using Autosynth. 🌈


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

```
2021-03-23 15:44:25,811 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-logging/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-23 15:44:26,773 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/f2ee7879-6acd-4e49-9063-a8d2e2b191f1/targets

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

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-logging.git",
-        "sha": "e4acb6c59805e92d244cdf907d9a50a77f82d269"
+        "sha": "de2d4425729eea0e48e0b88dce1ea186c060041e"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "8b13da943497f75c5303700bff5aabdd85d939e0"
+        "sha": "c84c8f156e09702e1c8946bfb9746e6f5892cf27"
       }
     }
   ]

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>2.1.5</version>
+  <version>2.2.0</version>
 </dependency>
 
 ```