img:auto_orient() is in magic.lua, but no a line in documentation

I spend 3 work days trying to realize auto rotate by EXIF info function for this library.
But it is in the library!!!

Please, note this in documentation!
You can use img:auto_orient() function to rotate images by EXIF info!

And check file /usr/local/share/lua/5.1/magick/wand/image.lua before you begin make some new functionality!