added styling to code snippet

Author: Tien "Mimi" Nguyen

src/collections/_documentation/platforms/android/migrate.md

@@ -71,7 +71,9 @@ Sentry.getContext().addTag("tagName", "tagValue");
 
 *New*:
 
-    Sentry.setTag("tagName", "tagValue");
+```java
+Sentry.setTag("tagName", "tagValue");
+```
 
 **Capture custom exception**