Add Kotlin to listed drivers on landing page card (#113)

Author: cbullinger

source/index.txt

@@ -64,7 +64,7 @@ Welcome to the MongoDB Documentation
       :icon-alt: Drivers icon
 
       Connect your application via MongoDB client libraries for Python,
-      Javascript, Typescript, Java, C#, Ruby, PHP, Go, and Rust.
+      Javascript, Typescript, Java, C#, Ruby, PHP, Go, Rust, and Kotlin.
 
    .. card::
       :headline: Tools and Connectors