chore: regenerate README (#1036)

This PR was generated using Autosynth. 🌈


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

```
2021-04-26 23:08:51,617 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerystorage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-04-26 23:08:52,912 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/bb16ccb1-518a-42a7-a428-a8e68bb9baaa/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": "7503dfa642548ebc12c2fcb1a83e88dd01e7a693"
+        "sha": "776c670267d2c9bbc730c41f8187ac853b8525d3"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "5a6f30b8bb7672cf237c4f75d5aa96bfba170e7f"
+        "sha": "a648ce0ca3fe122b3186d7e6861cb641437e485e"
       }
     }
   ]

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:1.20.0'
+compile 'com.google.cloud:google-cloud-bigquerystorage:1.20.1'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.20.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.20.1"
 ```
 
 ## Authentication