update contributing.md to reflect DCO instead of CLA (#1799)
update contributing.md to reflect DCO instead of CLA (#1799)

fixes getgauge/gauge-bot#16

Signed-off-by: sriv <65b0fe9e2897ee021ca8630a99a42376d4b8ffa5@gmail.com>
getgauge/gauge,getgauge/gauge,getgauge/gauge,getgauge/gauge,getgauge/gauge