[schema] WRED red max threshold and ECN modes

* Added support for specifying ECN mode values
* Added red_max_threshold

signed-off-by hrachya@mellanox.com

doc/swss-schema.md

@@ -256,18 +256,25 @@ and reflects the LAG ports into the redis under: `LAG_TABLE:<team0>:port`
 ###WRED\_PROFILE\_TABLE
 	; WRED profile
 	; SAI mapping - saiwred.h
-	key						= "WRED_PROFILE_TABLE:"name
+	key                     = "WRED_PROFILE_TABLE:"name
 	;field						value
-	yellow_max_threshold	= byte_count
-	green_max_threshold		= byte_count
-	byte_count				= 1*DIGIT
-
+	yellow_max_threshold    = byte_count
+	green_max_threshold     = byte_count
+	red_max_threshold       = byte_count
+	byte_count              = 1*DIGIT
+	ecn                     = "ecn_none" / "ecn_green" / "ecn_yellow" / "ecn_red" /  "ecn_green_yellow" / "ecn_green_red" / "ecn_yellow_red" / "ecn_all" 
+
 	Example:
 	127.0.0.1:6379> hgetall "WRED_PROFILE_TABLE:AZURE"
 	1) "green_max_threshold"
 	2) "20480"
 	3) "yellow_max_threshold"
 	4) "30720"
+	5) "red_max_threshold"
+	6) "1234"
+	7) "ecn"
+	8) "ecn_all"
+
 
 ----------------------------------------------
 ###TUNNEL_DECAP_TABLE