chore: regenerate README (#1161)

This PR was generated using Autosynth. 🌈


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

```
2021-06-30 23:18:26,457 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerystorage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-30 23:18:27,906 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/8ebbcc03-b92b-47df-9e69-32d6855a20c8/targets

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquerystorage.git",
-        "sha": "a0736fed9535c89a10ddd8b565f06aaafacc2c14"
+        "sha": "1f4c2b78ee39b1975be87592ff79cdea8a1ac633"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "1f9ceba741b6b4a60ce09ab98423e941f5bd47f2"
+        "sha": "39652e3948f455fd0b77535a0145eeec561a3706"
       }
     }
   ]

README.md

@@ -51,12 +51,12 @@ compile 'com.google.cloud:google-cloud-bigquerystorage'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-bigquerystorage:1.22.5'
+compile 'com.google.cloud:google-cloud-bigquerystorage:1.22.6'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.22.5"
+libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.22.6"
 ```
 
 ## Authentication