chore: regenerate README (#318)

This PR was generated using Autosynth. 🌈


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

```
2020-12-10 21:19:47,752 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-storage-nio/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2020-12-10 21:19:48,595 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/80816c0a-d6ae-44c0-954e-94bfc316a524/targets

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

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-storage-nio.git",
-        "sha": "1ee6bad68243410b9ce0e9793ca2a1eb89bfe328"
+        "sha": "2fd83844c4915d6b841257aaa3be32195277c1a8"
       }
     },
     {

README.md

@@ -42,7 +42,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-nio</artifactId>
-  <version>0.122.2</version>
+  <version>0.122.3</version>
 </dependency>
 
 ```