Change heatshield part category and tech node

For #108

Author: Robin Chang

GameData/SDHI/Service Module System/Parts/SDHI_2.5_Heatshield/part.cfg

@@ -17,10 +17,10 @@ PART
 	node_stack_top = 0.0, 0.15625, 0.0, 0.0, 1.0, 0.0, 2
 	node_stack_bottom = 0.0, -0.125, 0.0, 0.0, -1.0, 0.0, 2
 
-	TechRequired = specializedConstruction
+	TechRequired = advLanding
 	entryCost = 1000
 	cost = 200
-	category = Structural
+	category = Thermal
 	subcategory = 0
 	title = SDHI 2.5m Heat Shield
 	manufacturer = Sum Dum Heavy Industries Co., Ltd