Add initial prototype.

3-mid/opengl/source/lean/buffer/opengl-buffer-vertex.ads

@@ -0,0 +1,7 @@
+with
+     openGL.Buffer.general;
+
+package openGL.Buffer.vertex is new openGL.Buffer.general (base_Object   => Buffer.array_Object,
+                                                           Index         => Index_t,
+                                                           Element       => Site,
+                                                           Element_Array => Sites);