Update documentation of append

Author: koperagen

docs/StardustDocs/topics/append.md

@@ -2,10 +2,27 @@
 
 Adds one or several rows to [`DataFrame`](DataFrame.md)
 ```kotlin
-df.append (
+df.append(
     "Mike", 15,
     "John", 17, 
-    "Bill", 30)
+    "Bill", 30,
+)
+```
+
+If the compiler plugin enabled, typesafe overload of `append` is available for `@DataSchema` classes.
+
+```
+@DataSchema
+data class Person(val name: String, val age: Int)
+```
+
+```kotlin
+val df = dataFrameOf(
+    Person("Mike", 15),
+    Person("John", 17),
+)
+
+df.append(Person("Bill", 30))
 ```
 
 **Related operations**: [](appendDuplicate.md)