chore: regenerate README (#690)

This PR was generated using Autosynth. 🌈


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

```
2021-09-08 15:03:53,390 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-storage-nio/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-09-08 15:03:54,891 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/70ee51ce-240b-426e-a12b-0bc1602c65b3/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

Author: yoshi-automation

java-storage-nio/.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-storage-nio.git",
-        "sha": "4fd71b5156239e641552215dfc5bd31a5cce4a03"
+        "sha": "1c7b4c4a90d39303c1d51f4bb80d88dc7da00694"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "ad7fd76e17bf9494a3e47ff9cf445f61564432e0"
+        "sha": "17ee6e5c08f2eb47029beee4776ce990e56b3925"
       }
     }
   ]

java-storage-nio/README.md

@@ -53,7 +53,7 @@ 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:22.0.0')
+implementation platform('com.google.cloud:libraries-bom:23.0.0')
 
 implementation 'com.google.cloud:google-cloud-nio'
 ```