adding tutorial for spline

src/content/tutorials/en/intro-to-p5.spline.mdx

@@ -0,0 +1,23 @@
+---
+title: "Splines in p5.js: Curves, Sampling, and Shapes"
+description: Learn the full spline toolkit in p5.js, draw smooth curves, sample points and tangents, tune curvature, and build flowing shapes in 2D and 3D.
+category: "2.0"
+categoryIndex: 0
+featuredImage: ../images/featured/Intro-to-splines.png
+featuredImageAlt: ‘Intro to Splines’ title showing three colorful spline curves, labeled control points (p0-p3), and a tangent arrow.
+relatedContent:
+  references:
+    - en/p5/spline
+    - en/p5/splinepoint
+    - en/p5/splinetangent
+    - en/p5/splineproperty
+    - en/p5/splinevertex
+
+authors:
+  - Perminder Singh
+---
+
+import EditableSketch from "../../../components/EditableSketch/index.astro";
+import Callout from "../../../components/Callout/index.astro";
+
+## Introduction