Fixed typos in README.
Fixed typos in README.

chrisballinger/Onboard,hao-hua/Onboard,msdgwzhy6/Onboard,z8927623/Onboard,ixx1232/Onboard,lts1610/Onboard,ConnectX/Onboard,hawkinchina/onboard,gabrielPeart/Onboard,shahzadmajeed/Onboard,domenicosolazzo/Onboard,donpark/Onboard,lts1610/Onboard,mamaral/Onboard,alokard/Onboard,hao-hua/Onboard,oenius/Onboard,jianwoo/Onboard,jianwoo/Onboard,eeschimosu/Onboard,sirdharma/Onboard,hawkinchina/onboard,gaurav1981/Onboard,ngocphu2810/Onboard,takaaptech/Onboard,lfarah/Onboard,cyupa/Onboard,jason790/Onboard