chore: regenerate README (#547)

This PR was generated using Autosynth. 🌈


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

```
2021-06-02 20:14:29,018 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-logging/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-02 20:14:30,270 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/c027b477-c066-4de4-ae1f-a7f2dad022da/targets

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Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-logging.git",
-        "sha": "3044f761d15379a08a021b07fb3d754d22536da3"
+        "sha": "d3bd6440e378d645a8ae5ccef6a89cc772c21edc"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "a2de127f90799cd5bace653b1dcc5dd2ca8b19c9"
+        "sha": "c3e41da0fa256ad7f6b4bc76b9d069dedecdfef4"
       }
     }
   ]

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>2.2.3</version>
+  <version>2.3.0</version>
 </dependency>
 
 ```
@@ -52,12 +52,12 @@ compile 'com.google.cloud:google-cloud-logging'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-logging:2.2.3'
+compile 'com.google.cloud:google-cloud-logging:2.3.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-logging" % "2.2.3"
+libraryDependencies += "com.google.cloud" % "google-cloud-logging" % "2.3.0"
 ```
 
 ## Authentication