Add descriptions to demos

orx-shapes/src/jvmDemo/kotlin/hobbycurve/DemoHobbyCurve04.kt

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+package hobbycurve
+
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.extra.noise.scatter
+import org.openrndr.extra.shapes.hobbycurve.hobbyCurve
+import org.openrndr.extra.shapes.ordering.hilbertOrder
+import kotlin.random.Random
+
+/**
+ * Demonstrates the use of the `tensions` argument when creating a Hobby curve.
+ *
+ * The program starts by creating a random set of scattered points with enough separation between them.
+ * The points are sorted using `hilbertOrder` to minimize the travel distance when visiting all the points.
+ * Finally, we draw a set of 40 hobby translucent curves using those same points but with varying tensions.
+ */
+fun main() = application {
+    configure {
+        width = 720
+        height = 720
+    }
+    program {
+        extend {
+            for (i in -20..20) {
+                val t = i / 10.0
+                val points = drawer.bounds.offsetEdges(-50.0)
+                    .scatter(25.0, random = Random(0))
+                    .hilbertOrder()
+
+                drawer.stroke = ColorRGBa.WHITE.opacify(0.5)
+                drawer.fill = null
+                drawer.contour(hobbyCurve(points, closed = false, tensions = { i, inAngle, outAngle ->
+                    Pair(t, t)
+                }))
+            }
+        }
+    }
+}