Congratulations on having such a bright child! I'm sure your love of reading has a lot to do with her reading success.
I am a certified elementary school teacher and I think your daughter will be fine if she stays where she is. As educators we are trained to teach to the entire class, not just the middle group. We have strategies to help bring below grade level readers up to speed and to extend lessons for the children who are reading abve grade level.
Ask your daughter's teacher what kinds of things she will do as far as extension activities. Ask her what you can do at home as well.
In my experience, skipping grades is not usually the best course. Kindergarten is about a lot more than just reading. If your daughter moved up to first grade, she'd miss out on the base lessons in all the subject areas. Plus, kindergarten is FUN!
Personally, my daughter is the "highest" reader in her class. My hope is that she doesn't always feel like she is the smartest and that school is easy. I have seen third graders who always excelled in earlier grades really struggle in later elementary because they never had to study before. That's why I feel extension is so important.
Finally, you'll know if your daughter is bored if she starts getting into trouble. The gifted teachers tell their students "boredom is a choice." Next year, your daughter will take the CoGat which is basically an IQ test. That will give you more information. Ask your daughter's teacher if you can observe the class. See what things your daughter is doing. You'll probably see that Kindergarten is a very busy place where a lot of learning is taking place. Next year you can do the same thing. Above all, relax and enjoy these times. Before we know it, we'll be helping with research papers!
Good luck!