Spigot/BukkitDev/etc. links.

I think most of them use my shortlink (r.robomwm.com/GPWiki which I guess I made before I owned griefprevention.com) currently so it should be relatively easy to update for now.

• shortlink
• spigot (seems to only use shortlink)
• bukkitdev

Created https://r.griefprevention.com/docs which currently points to legacy docs.