docs(examples): create vertex_displacement example

examples/shaders/vertex_displacement/glsl100/vertex_displacement.fs

@@ -0,0 +1,18 @@
+#version 100
+
+precision mediump float;
+
+// Input vertex attributes (from fragment shader)
+varying vec2 fragTexCoord;
+varying float height;
+
+
+void main()
+{
+    vec4 darkblue = vec4(0.0, 0.13, 0.18, 1.0);
+    vec4 lightblue = vec4(1.0, 1.0, 1.0, 1.0);
+    // Interpolate between two colors based on height
+    vec4 finalColor = mix(darkblue, lightblue, height);
+
+    gl_FragColor = finalColor;
+}