docs: new libraries-bom (#1025)

@thiagotnunes @suztomo

Author: elharo

README.md

@@ -17,7 +17,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>19.2.0</version>
+      <version>19.2.1</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -45,7 +45,7 @@ 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:19.2.0')
+implementation platform('com.google.cloud:libraries-bom:19.2.1')
 
 compile 'com.google.cloud:google-cloud-spanner'
 ```