Fix XSS vulnerability in link regex [Security Issue]
Fix XSS vulnerability in link regex [Security Issue]

jackycute/HackMD,hackmdio/hackmd,Yukaii/hackmd,hackmdio/hackmd,aswathyjacob8/newtest,ironhack/hackmd,Yukaii/hackmd,Rwing/hackmd,jackycute/HackMD,jackycute/HackMD,hackmdio/hackmd,Rwing/hackmd,PeterDaveHello/hackmd,PeterDaveHello/hackmd,ironhack/hackmd,PeterDaveHello/hackmd,Rwing/hackmd,Yukaii/hackmd,ironhack/hackmd,aswathyjacob8/newtest,aswathyjacob8/newtest