Update Northern Russia campaign.

I bumped the submitted 6.1 to 7.0 (which didn't exist when the files
were uploaded) because this campaign uses no scenery targets.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/1318

resources/campaigns/northern_russia.json

@@ -2,10 +2,10 @@
   "name": "Caucasus - Northern Russia",
   "theater": "Caucasus",
   "authors": "Plob",
-  "recommended_player_faction": "USA 2005",
-  "recommended_enemy_faction": "Russia 1990",
-  "description": "<p>A medium campaign through the north eastern part of the Caucasus map.</p><p>Russia has invaded Georgia through the eastern mountains. Mount a counter offense and push them back!",
+  "recommended_player_faction": "Bluefor Modern",
+  "recommended_enemy_faction": "Russia 1975",
+  "description": "<p>A medium campaign through the north eastern part of the Caucasus map. Play vs 1975 Russia for an low-medium difficulty campaign, play vs russia 1990 for a hard difficulty campaign. </p><p>Russia has invaded Georgia through the eastern mountains. Mount a counter offense and push them back!",
   "miz": "northern_russia.miz",
   "performance": 2,
-  "version": "6.0"
+  "version": "7.0"
 }