add showcase for Gravitational attraction

Author: vislupus

content/videos/noc/2-forces/5-gravitational-attraction/showcase/contribution3.json

@@ -0,0 +1,9 @@
+{
+  "title": "Gravitational attraction",
+  "author": {
+    "name": "Nikola Bozhinov",
+    "url": "https://github.com/vislupus"
+  },
+  "url": "https://vislupus.github.io/p5-simulations/gravitational_attraction.html",
+  "submittedOn": "2025-01-10"
+}

content/videos/noc/2-forces/5-gravitational-attraction/showcase/contribution3.png

@@ -0,0 +1,9 @@
+{
+  "title": "Solar System",
+  "author": {
+    "name": "Nikola Bozhinov",
+    "url": "https://github.com/vislupus"
+  },
+  "url": "https://vislupus.github.io/p5-simulations/solar_system.html",
+  "submittedOn": "2025-01-10"
+}