Add descriptions to demos

orx-timer/src/demo/kotlin/DemoRepeat01.kt

@@ -1,6 +1,14 @@
 import org.openrndr.application
 import org.openrndr.extra.timer.repeat
 
+/**
+ * A simple demonstration on using the `repeat` method to execute a function
+ * at regular intervals.
+ *
+ * Note that drawing inside the repeat action has no effect.
+ * See DemoRepeat02.kt to learn how to trigger drawing.
+ *
+ */
 fun main() = application {
     program {
         repeat(2.0) {

orx-timer/src/demo/kotlin/DemoRepeat02.kt

@@ -4,7 +4,7 @@ import org.openrndr.events.Event
 import org.openrndr.extra.timer.repeat
 
 /**
- * This demonstrates how to combine `repeat {}` with a postponed event to trigger drawing
+ * This demonstrates how to combine `repeat {}` with a postponed event to trigger drawing.
  */
 
 fun main() = application {

orx-timer/src/demo/kotlin/DemoRepeat03.kt

@@ -0,0 +1,25 @@
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.extra.timer.repeat
+
+/**
+ * Shows how a `repeat` block can update a variable used
+ * for rendering. In this demo, the `opacity` variable is
+ * reduced on every animation frame, and increased to 1.0
+ * every 2 seconds, creating a pulsating animation effect.
+ */
+fun main() = application {
+    program {
+        var opacity = 0.0
+        repeat(2.0) {
+            opacity = 1.0
+        }
+        extend {
+            drawer.clear(ColorRGBa.PINK)
+            drawer.stroke = ColorRGBa.BLACK.opacify(opacity)
+            drawer.fill = ColorRGBa.WHITE.opacify(opacity)
+            drawer.circle(width / 2.0, height / 2.0, 200.0)
+            opacity *= 0.9
+        }
+    }
+}

orx-timer/src/demo/kotlin/DemoTimeOut01.kt

@@ -1,6 +1,13 @@
 import org.openrndr.application
 import org.openrndr.extra.timer.timeOut
 
+/**
+ * Demonstrates the `timeOut` function.
+ *
+ * It is similar to the `repeat` function,
+ * but it runs only once after the specified delay in seconds.
+ *
+ */
 fun main() = application {
     program {
         timeOut(2.0) {