Update README.md

feat(tooltip): added tooltip for each element in the pie chart

feat(click): added click event and deleting item on click

feat(transitions): added named transitions

feat(onevents): added mouseover and mouseout events

feat(legend): added custom tweens and d3 legend

feat(comments): updated comments

feat(addtweens): added enter and exit tweens with duration

feat(piechart): added piechart

feat(files): added basic files for project

Initial commit