Some wiki documentation for declarative mod compatibility (#9990)

docs/Modders/Images-and-Audio.md

@@ -7,6 +7,8 @@ It is either selected for the current game (during new game creation, cannot be
 _Or_ it is marked as 'Permanent audiovisual mod' in the mod manager (you must select it in the 'installed' column to get the checkbox).
 In that case only graphics and audio will be active, the rule changes will be ignored (if it contains any) unless the first way is _also_ used.
 
+Note that the Mod author can (and often should) control whether the checkbox appears using [ModOptions](Mod-file-structure/5-Miscellaneous-JSON-files.md#modoptionsjson) [uniques](uniques.md#modoptions-uniques).
+
 ## Override built-in graphics
 
 If a mod supplies an image with the same name and path as one included in the base game (and its [atlas](Mods.md#more-on-images-and-the-texture-atlas) is up to date), and the mod is active, the mod's graphics will be used instead of the built-in one.

docs/Modders/Mod-file-structure/5-Miscellaneous-JSON-files.md

@@ -108,6 +108,9 @@ This file is a little different:
 -   Does not exist in Vanilla ruleset
 -   Is entirely optional but will be created after downloading a mod
 
+Note that this file controls _declarative mod compatibility_ (Work in progress) - e.g. there's [uniques](../uniques.md#modoptions-uniques) to say your Mod should only or never be used as 'Permanent audiovisual mod'.
+Incompatibility filtering works so far between extension and base mods, but feel free to document known extension-to-extension incompatibilities using the same Unique now. Stay tuned!
+
 The file can have the following attributes, including the values Unciv sets (no point in a mod author setting those):
 
 | Attribute           | Type    | Optional | Notes                                                                                                                                                                               |