Caged/d3-tip — pull request #57 by bkg (2014-03-28 03:45:30+00:00)
Title: update documentation with an offset callback example

Hi, here is a small addition to the documentation with an example of passing a callback to ```tip.offset()``` for dynamically positioning the tip. This came in handy when adding tips to variously shaped polygons so I hope it will be useful to others as well.