Add helpful page for game support

app/flatpages/help.md

@@ -19,6 +19,7 @@ toc: False
 * [Git Update Detection](update_config)
 * [Creating Releases using Webhooks](release_webhooks)
 * [Package Configuration and Releases Guide](package_config)
+* [Supported Games](game_support)
 
 ## Help for Specific User Ranks
 

app/flatpages/help/game_support.md

@@ -0,0 +1,37 @@
+title: Supported Games
+
+<p class="alert alert-warning">
+    This feature is experimental
+</p>
+
+## Why?
+
+The supported/compatible games feature allows mods to specify the games that they work with, which improves
+user experience.
+
+
+## Support sources
+
+### mod.conf
+
+You can use `supported_games` to specify games that your mod is compatible with.
+
+You can use `unsupported_games` to specify games that your mod doesn't work with, which is useful for overriding
+ContentDB's automatic detection.
+
+Both of these are comma-separated lists of game technical ids. Any `_game` suffixes are ignored, just like in Minetest.
+
+    supported_games = minetest_game, repixture
+    unsupported_games = lordofthetest, nodecore, whynot
+
+### Dependencies
+
+ContentDB will analyse hard dependencies and work out which games a mod supports.
+
+This uses a recursive algorithm that works out whether a dependency can be installed independently, or if it requires
+a certain game.
+
+
+## Combining all the sources
+
+mod.conf will override anything ContentDB detects.