add mi439 twrp name (#363)

Should partially fix
#352

Author: tsterbak

openandroidinstaller/assets/configs/Mi439.yaml

@@ -15,8 +15,7 @@ metadata:
     - olive
     - olivelite
     - olivewood
-  notes:
-    - Be careful when choosing OrangeFox version, Android 12 & 13 ROM needs OrangeFox version code with `A12`, for example `R11.1_5_A12`. Android 10 & 11 ROM needs OrangeFox version code without `A12` (bellow on the page)
+  twrp-link: mi439
 requirements:
   firmware: MiUI 12.5 (Q)
 steps: