Changing examples to use makefile

- Testing a modified version of the makefile from raylib Instead of multiple project files for examples.
- Fixed readme example

Examples/Examples/models/resources/shaders/skybox.fs

@@ -1,31 +0,0 @@
-/*******************************************************************************************
-*
-*   rPBR [shader] - Background skybox fragment shader
-*
-*   Copyright (c) 2017 Victor Fisac
-*
-**********************************************************************************************/
-
-#version 330
-
-// Input vertex attributes (from vertex shader)
-in vec3 fragPos;
-
-// Input uniform values
-uniform samplerCube environmentMap;
-
-// Output fragment color
-out vec4 finalColor;
-
-void main()
-{
-    // Fetch color from texture map
-    vec3 color = texture(environmentMap, fragPos).rgb;
-
-    // Apply gamma correction
-    color = color/(color + vec3(1.0));
-    color = pow(color, vec3(1.0/2.2));
-
-    // Calculate final fragment color
-    finalColor = vec4(color, 1.0);
-}