Add descriptions to demos

orx-jvm/orx-gui/src/demo/kotlin/DemoPath01.kt

@@ -4,6 +4,18 @@ import org.openrndr.extra.parameters.Description
 import org.openrndr.extra.parameters.PathParameter
 import org.openrndr.extra.propertywatchers.watchingImagePath
 
+/**
+ * Demonstrates how to include a button for loading images in a GUI, and how to display
+ * the loaded image.
+ *
+ * The program applies the `@PathParameter` annotation to a `String` variable, which gets
+ * rendered by the GUI as an image-picker button. Note the allowed file `extensions`.
+ *
+ * This mechanism only updates the `String` containing the path of an image file.
+ *
+ * The `watchingImagePath()` delegate property is used to automatically load an image
+ * when its `String` argument changes.
+ */
 fun main() = application {
     program {
         val gui = GUI()