Add documentation for difficulty.json

docs/modders/Difficulty.md

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+< [Documentation](../Readme.md) / [Modding](Readme.md) / Difficulty
+
+
+Since VCMI 1.4.0 there are more capabilities to configure difficulty parameters.
+It means, that modders can give different bonuses to AI or human players depending on selected difficulty
+
+Difficulty configuration is located in [config/difficulty.json](../config/difficulty.json) file and can be overriden by mods.
+
+## Format summary
+
+``` javascript
+{
+	"human": //parameters impacting human players only
+	{
+		"pawn": //parameters for specific difficulty
+		{
+			//starting resources
+			"resources": { "wood" : 30, "mercury": 15, "ore": 30, "sulfur": 15, "crystal": 15, "gems": 15, "gold": 30000, "mithril": 0 },
+			//bonuses will be given to player globaly
+			"globalBonuses": [],
+			//bonuses will be given to player every battle
+			"battleBonuses": []
+		},
+		"knight": {},
+		"rook": {},
+		"queen": {},
+		"king": {},
+	},
+	"ai": //parameters impacting AI players only
+	{
+		"pawn": {}, //parameters for specific difficulty 
+		"knight": {},
+		"rook": {},
+		"queen": {},
+		"king": {},
+	}
+}
+```
+
+## Bonuses
+
+It's possible to specify bonuses of two types: `globalBonuses` and `battleBonuses`.
+
+Both are arrays containing any amount of bonuses, each can be described as usual bonus. See details in [bonus documenation](Bonus_Format.md).
+
+`globalBonuses` are given to player on the begining and depending on bonus configuration, it can behave diffierently.
+
+`battleBonuses` are given to player during the battles, but *only for battles with neutral forces*. So it won't be provided to player for PvP battles and battles versus AI heroes/castles/garrisons. To avoid cumulative effects or unexpected behavior it's recommended to specify bonus `duration` as `ONE_BATTLE`.
+
+For both types of bonuses, `source` should be specified as `OTHER`.
+
+## Example
+
+```js
+{ //will give 150% extra health to all players' creatures if specified in "battleBonuses" array
+	"type" : "STACK_HEALTH",
+	"val" : 150,
+	"valueType" : "PERCENT_TO_ALL",
+	"duration" : "ONE_BATTLE",
+	"sourceType" : "OTHER"
+},
+```
+
+## Compatibility
+
+Starting from VCMI 1.4 `startres.json` is not available anymore and will be ignored if present in any mod.
+Thus, `Resourceful AI`  mod of version 1.2 won't work anymore.