chore: regenerate README (#994)

This PR was generated using Autosynth. 🌈


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

```
2021-04-10 14:11:05,943 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerystorage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-04-10 14:11:07,198 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/37724ddd-0f6e-40e4-91f3-ddd536c0a98e/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": "44c0aeffa489aa67552be8a252e552d0c83685d9"
+        "sha": "ca38348b7c7a88454c6fbe42957b6a9a5dd9d040"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "4501974ad08b5d693311457e2ea4ce845676e329"
+        "sha": "0a071b3460344886297a304253bf924aa68ddb7e"
       }
     }
   ]

README.md

@@ -38,7 +38,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-bigquerystorage</artifactId>
-  <version>1.17.0</version>
+  <version>1.18.0</version>
 </dependency>
 
 ```
@@ -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:1.17.0'
+compile 'com.google.cloud:google-cloud-bigquerystorage:1.18.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.17.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.18.0"
 ```
 
 ## Authentication