If you want to make a link that any given front end will use just knock the domain off. peakd does something slightly different with community pages though, like for me the OCA community link is https://peakd.com/c/hive-156509, to make a link that will work in most front ends without directing I'd do a link like [OnChainArt](/created/hive-156509), which will still work in peakd but it will put up a note asking if you want to go to the community page (peakd community pages look better anyway XD).