Document aircraft modding changes in 7.

Modded-Aircraft-Support.md

@@ -141,11 +141,60 @@ For campaign start setup and mod settings support, add your plane to the files [
         modLayout.addWidget(frenchpack, 6, 1)
 ```
 
-## Step 3 : Liberation flight planner database setup : 
+## Step 3 : Liberation flight planner database setup:
+
+### DCS Liberation 7
+
+The aircraft preferences per task are kept in each aircraft's yaml file in `resources/units/aircraft/*.yaml`. Each task is assigned a weight describing the aircraft's relative strength at the given task. Aircraft with a higher weight for a given task will be preferred over those with a lower weight. If a task is omitted from the yaml file, the aircraft will not be capable of performing that mission type. For example:
+
+```yaml
+# From FA-18C_hornet.yaml
+tasks:
+  Anti-ship: 150
+  BAI: 740
+  BARCAP: 450
+  CAS: 740
+  DEAD: 440
+  Escort: 450
+  Fighter sweep: 450
+  Intercept: 450
+  OCA/Aircraft: 740
+  OCA/Runway: 600
+  SEAD: 160
+  SEAD Escort: 160
+  Strike: 600
+  TARCAP: 450
+```
+
+```yaml
+# From F-16C_50.yaml
+tasks:
+  BAI: 750
+  BARCAP: 460
+  CAS: 750
+  DEAD: 450
+  Escort: 460
+  Fighter sweep: 460
+  Intercept: 460
+  OCA/Aircraft: 750
+  OCA/Runway: 610
+  SEAD: 170
+  SEAD Escort: 170
+  Strike: 610
+  TARCAP: 460
+```
+
+The hornet has a BAI weight of 740 while the viper has a BAI weight of 750. Liberation will prefer choosing vipers to hornets when deciding which aircraft is better suited to BAI.
+
+Aircraft can have identical weights for a task. When multiple aircraft have the same weight for a task, they are treated as equal by Liberation. Selection criteria vary by many factors; one may be chosen randomly from the set of equal aircraft, one may be chosen arbitrarily, or a different but similar aircraft may be chosen. **These weights are only guidelines.** Use them to give Liberation hints about which aircraft are better at each task.
+
+For an overview of all tasks and weights in Liberation, run `dcs_liberation.exe dump-task-priorities` (from the command line). That will dump `Liberation/Debug/priorities.yaml` to your DCS Saved Games directory.
+
+### DCS Liberation 6
 
 Open [ai_flight_planner_db.py](https://github.com/dcs-liberation/dcs_liberation/blob/develop/gen/flights/ai_flight_planner_db.py)
 
-Add your plane to the lists it needs to be in, so DCS Liberation is aware of its capabilities : 
+Add your plane to the lists it needs to be in, so DCS Liberation is aware of its capabilities. **These lists are in priority order**: 
 
 **Example:**