Improve documentation for recursion example

src/data/examples/en/00_Structure/08_Recursion.js

@@ -1,8 +1,10 @@
 /*
  *@name Recursion
  *@description A demonstration of recursion, which means functions call themselves.
- * Notice how the drawCircle() function calls itself at the end of its block.
- * It continues to do this until the variable "level" is equal to 1.
+ * A recursive function must have a terminating condition, without which it will
+ * go into an infinite loop. Notice how the drawCircle() function calls itself 
+ * at the end of its block. It continues to do this until the variable "level" is 
+ * equal to 1.
  */
 
 function setup() {
@@ -16,11 +18,17 @@ function draw() {
 }
 
 function drawCircle(x, radius, level) {
+  // 'level' is the variable that terminates the recursion once it reaches 
+  // a certain value (here, 1). If a terminating condition is not 
+  // specified, a recursive function keeps calling itself again and again
+  // until it runs out of stack space - not a favourable outcome! 
   const tt = (126 * level) / 4.0;
   fill(tt);
   ellipse(x, height / 2, radius * 2, radius * 2);
-  if (level > 1) {
-    level = level - 1;
+  if (level > 1) {  
+    // 'level' decreases by 1 at every step and thus makes the terminating condition
+    // attainable
+    level = level - 1;  
     drawCircle(x - radius / 2, radius / 2, level);
     drawCircle(x + radius / 2, radius / 2, level);
   }