chore: regenerate README (#581)

This PR was generated using Autosynth. 🌈


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

```
2020-10-23 18:04:36,327 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-storage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-23 18:04:37,272 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/a49d43ba-c93e-41ce-bdb5-af0a037fa4bb/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": "5e49013add340e4d8287e00b8d4a9c499df80205"
+        "sha": "38dc36ff4c4683c4de1f5b184b4f438f8be322cf"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f96d3b455fe27c3dc7bc37c3c9cd27b1c6d269c8"
+        "sha": "721a7d2abb129029eca9d85a40da6eb7b8b1739a"
       }
     }
   ]

README.md

@@ -17,7 +17,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>13.1.0</version>
+      <version>13.2.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>