fix grammer errors
fix grammer errors

jackycute/HackMD,Rwing/hackmd,hackmdio/hackmd,Rwing/hackmd,ironhack/hackmd,PeterDaveHello/hackmd,jackycute/HackMD,hackmdio/hackmd,Yukaii/hackmd,ironhack/hackmd,hackmdio/hackmd,ironhack/hackmd,Rwing/hackmd,Yukaii/hackmd,PeterDaveHello/hackmd,jackycute/HackMD,PeterDaveHello/hackmd,Yukaii/hackmd