Fixed a typo in documentation
Fixed a typo in documentation

changed "...truncatedCode..." to "...truncatedCone..." in documentation

WebSeed/twgl.js,eyeccc/twgl.js,beni55/twgl.js,greggman/twgl.js,greggman/twgl.js,ptpham/twgl.js,beni55/twgl.js,greggman/twgl.js,WebSeed/twgl.js,eyeccc/twgl.js,ptpham/twgl.js