Old stable release download link in README

[hsandt]

Looks like README Stable links point to x86_64 and i686 which are v0.4 instead of the latest v0.5.

v0.5 itself is from 2014 so I suppose the best is still to take dev...

Said dev links from drone.io are dead though, so you need to download/clone the repository anyway.

EDIT: Ah, I see that v0.5 has no released deb packages... Should we make one? We may as well make a new release? I'm trying to build on my side but I'll need sqlite3 and deadbeef dev files, will do later...