chore: add kotlin version of code

Author: dcangulo

versioned_docs/version-6.x/getting-started.md

@@ -74,6 +74,9 @@ work on Android devices. Edit `MainActivity.java` file which is located in `andr
 
 Add the highlighted code to the body of `MainActivity` class:
 
+<details open>
+<summary>Java</summary>
+
 ```java {3-6}
 public class MainActivity extends ReactActivity {
   // ...
@@ -84,6 +87,21 @@ public class MainActivity extends ReactActivity {
   // ...
 }
 ```
+</details>
+
+<details>
+<summary>Kotlin</summary>
+
+```kotlin {3-5}
+class MainActivity: ReactActivity() {
+    // ...
+    override fun onCreate(savedInstanceState: Bundle?) {
+      super.onCreate(null);
+    }
+    // ...
+}
+```
+</details>
 
 and make sure to add the following import statement at the top of this file below your package statement:
 

versioned_docs/version-7.x/getting-started.md

@@ -74,6 +74,9 @@ work on Android devices. Edit `MainActivity.java` file which is located in `andr
 
 Add the highlighted code to the body of `MainActivity` class:
 
+<details open>
+<summary>Java</summary>
+
 ```java {3-6}
 public class MainActivity extends ReactActivity {
   // ...
@@ -84,6 +87,21 @@ public class MainActivity extends ReactActivity {
   // ...
 }
 ```
+</details>
+
+<details>
+<summary>Kotlin</summary>
+
+```kotlin {3-5}
+class MainActivity: ReactActivity() {
+    // ...
+    override fun onCreate(savedInstanceState: Bundle?) {
+      super.onCreate(null);
+    }
+    // ...
+}
+```
+</details>
 
 and make sure to add the following import statement at the top of this file below your package statement: