better comments

mandelbrot.c

@@ -28,8 +28,12 @@ void drawmandelbrot(SDL_Surface *surface) {
     bool diverges = false;
     float complex z = 0;
     int it;
-    for (it = 1; it < 256; it++) {
+    const int max_it = 170;
+    for (it = 1; it <= max_it; it++) {
+      /* z = z² + c */
       z = cpowf(z, 2) + c;
+
+      /* If |z| ever gets greater than 2, it diverges. */
       if (cabs(z) > 2) {
         diverges = true;
         break;