chore: regenerate README (#705)

This PR was generated using Autosynth. 🌈


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

```
2021-02-10 17:05:39,221 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-storage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-10 17:05:40,098 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/ede69408-84cc-4f58-a4ea-58ab9d4e69e8/targets

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

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-storage.git",
-        "sha": "631cb7f605e55682e82072eb39dcacbf6dab741d"
+        "sha": "2af8dfd95cdebc9e4d8252b0bbe3f092844d9f2c"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "b259489b06b25f399768b74b8baa943991f38ea7"
+        "sha": "2414b817065726eae0bc525346c7e874f969369d"
       }
     }
   ]

README.md

@@ -45,7 +45,7 @@ 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:16.3.0')
+implementation platform('com.google.cloud:libraries-bom:16.4.0')
 
 compile 'com.google.cloud:google-cloud-storage'
 ```