chore: regenerate README (#460)

This PR was generated using Autosynth. 🌈


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

```
2021-03-04 16:07:06,941 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-logging/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-04 16:07:07,911 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/0b944fcb-336c-4073-af71-6856c2e846a3/targets

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

Author: yoshi-automation

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-logging.git",
-        "sha": "0d325e843781f62e269b286561d9bd0b599118af"
+        "sha": "28a9f92171ecf75a23e5d89565f3023e5fcc6653"
       }
     },
     {

README.md

@@ -46,7 +46,7 @@ If you are using Maven without BOM, add this to your dependencies:
 
 If you are using Gradle 5.x or later, add this to your dependencies
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:18.1.0')
+implementation platform('com.google.cloud:libraries-bom:19.0.0')
 
 compile 'com.google.cloud:google-cloud-logging'
 ```