chore: regenerate README (#310)

This PR was generated using Autosynth. 🌈


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

```
2021-01-26 06:01:31,556 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-logging-logback/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-01-26 06:01:32,512 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/36e4c733-d2d0-480c-86f1-e66bbe4ca9cc/targets

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

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-logging-logback.git",
-        "sha": "89da31a819939dee982620b42e2e69d658e5f088"
+        "sha": "dfe6c69665dcd8eadb073758d10017e22528848c"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "16ec872dd898d7de6e1822badfac32484b5d9031"
+        "sha": "3816b080296d4d52975079fd26c110dd26ba25af"
       }
     }
   ]

README.md

@@ -20,18 +20,18 @@ If you are using Maven, add this to your pom.xml file:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-logging-logback</artifactId>
-  <version>0.119.4-alpha</version>
+  <version>0.119.6-alpha</version>
 </dependency>
 ```
 
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-logging-logback:0.119.4-alpha'
+compile 'com.google.cloud:google-cloud-logging-logback:0.119.6-alpha'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-logging-logback" % "0.119.4-alpha"
+libraryDependencies += "com.google.cloud" % "google-cloud-logging-logback" % "0.119.6-alpha"
 ```
 
 ## Authentication