feat(csgoserver) Add mapgroup and map example for the new Danger Zone map: Sirocco (#2323)

Co-authored-by: Borzák Attila <1230402+borzaka@users.noreply.github.com>

This new map Sirocco introduced to the game on 2019.04.30.
Plus add note to not use other mapgroups with Danger Zone mode.

lgsm/config-default/config-lgsm/csgoserver/_default.cfg

@@ -10,7 +10,7 @@
 
 ## Server Start Settings | https://docs.linuxgsm.com/configuration/start-parameters
 # https://developer.valvesoftware.com/wiki/Counter-Strike:_Global_Offensive_Dedicated_Servers#Starting_the_Server
-# [Game Modes]			gametype	gamemode	mapgroup (you can mix these across Game Modes, but use only one)
+# [Game Modes]			gametype	gamemode	mapgroup (you can mix these across all Game Modes except Danger Zone, but use only one)
 # Arms Race				1			0			mg_armsrace
 # Classic Casual		0			0			mg_casualsigma, mg_casualdelta
 # Classic Competitive	0			1			mg_active, mg_reserves, mg_hostage, mg_de_dust2
@@ -18,7 +18,7 @@
 # Deathmatch			1			2			mg_deathmatch
 # Demolition			1			1			mg_demolition
 # Wingman				0			2			
-# Danger Zone			6			0			mg_dz_blacksite (map: dz_blacksite)
+# Danger Zone			6			0			mg_dz_blacksite (map: dz_blacksite), mg_dz_sirocco (map: dz_sirocco)
 gametype="0"
 gamemode="0"
 mapgroup="mg_active"