Added a new task for 'var & val'

Programming Basics/var & val/Exercise 2/src/Task.kt

@@ -0,0 +1,7 @@
+fun main() {
+  var a = 10
+  val b = a
+  a = 42
+  println(a)
+  println(b)
+}

Programming Basics/var & val/Exercise 2/task-info.yaml

@@ -0,0 +1,6 @@
+type: edu
+files:
+- name: src/Task.kt
+  visible: true
+- name: test/output.txt
+  visible: false

Programming Basics/var & val/Exercise 2/task.md

@@ -0,0 +1,5 @@
+## `var` & `val` (#2)
+
+Define `var a = 10`. Now define a `val b = a`.
+After that, assign `42` to `a` and display both `a` and `b`
+(the output will be in different lines).

Programming Basics/var & val/Exercise 2/test/output.txt

@@ -0,0 +1,2 @@
+42
+10

Programming Basics/var & val/lesson-info.yaml

@@ -1,6 +1,7 @@
 content:
 - Examples
 - Exercise 1
+- Exercise 2
 - Exercise 3
 - Exercise 4
 - Exercise 5