Improves desc of riot shotgun
Defines riot shotgun for spawn in the armory
Makes riot shotgun unique
Merge branch 'master' of https://github.com/tgstation/-tg-station into thesetypofixesdedicatedtoshakespeare

Conflicts:
	icons/obj/gun.dmi
Merge pull request #5231 from Jordie0608/thesetypofixesdedicatedtoshakespeare

[MAP] Adds riot shotgun for spawn in armory