Updated Subaru (markdown)

Subaru.md

@@ -80,4 +80,20 @@ Drives
 
 WIP models support is incomplete and untested
 - current state https://github.com/martinl/openpilot/tree/subaru-PR-test
-- open issues https://github.com/martinl/openpilot/issues
+- open issues https://github.com/martinl/openpilot/issues
+
+## Harness pin swap
+
+Following models need a pin swap on 26-pin Comma Car Harness connector
+ - 2020+ Outback
+ - 2020+ Legacy
+ - Crosstrek Hybrid
+
+### Pin swap guide
+
+<img width="408" alt="subaru-outback-2020-pin-swap" src="https://user-images.githubusercontent.com/148686/115105836-19046400-9f6a-11eb-9bbd-3d14309861d2.png">
+
+- 4 <> 8, Can0 High with Can1 High
+- 6 <> 10, Can0 Low with Can1 Low
+- 18 <> 22, Can1 High with Can2 High
+- 20 <> 24, Can1 Low with Can2 Low