doc changes and reference folder

docs/features/XML_SYSTEM.md

@@ -24,6 +24,7 @@ The schema supports:
 - query port calculation
 - control protocol selection
 - mod definitions
+- Workshop / Server Content capability declarations
 - custom fields
 - server parameter groups
 - text replacement helpers
@@ -89,6 +90,50 @@ XML definitions also feed:
 - reserved ports
 - mod or content behavior
 
+## Workshop / Server Content Capability
+
+Workshop-enabled games must use the canonical `workshop_support` block. Loose top-level tags such as `workshop_app_id` are compatibility parser fallbacks only and should not be used in new game XML because schema validation is intentionally strict.
+
+Example:
+
+```xml
+<workshop_support>
+  <enabled>1</enabled>
+  <provider>steam</provider>
+  <steam_app_id>107410</steam_app_id>
+  <workshop_app_id>107410</workshop_app_id>
+  <download_method>steamcmd</download_method>
+  <install_strategy>arma_mod_folder</install_strategy>
+  <install_path>{SERVER_ROOT}/{MOD_FOLDER}</install_path>
+  <startup_param_format>-mod={MOD_LIST}</startup_param_format>
+  <mod_separator>;</mod_separator>
+  <mod_prefix>@</mod_prefix>
+  <copy_keys enabled="1">
+    <source_pattern>{MOD_PATH}/keys/*.bikey</source_pattern>
+    <target_path>{SERVER_ROOT}/keys</target_path>
+  </copy_keys>
+</workshop_support>
+```
+
+Supported `install_strategy` values:
+
+- `game_managed_workshop`
+- `steamcmd_download_only`
+- `copy_to_game_root`
+- `copy_to_mod_folder`
+- `dayz_mod_folder`
+- `arma_mod_folder`
+- `config_only`
+- `custom_scripted_install`
+
+`workshop_app_id` is the Steam Workshop app ID used by `steamcmd +workshop_download_item`. It is not automatically the same as a dedicated server installer app ID. For Arma 3, Workshop content uses `107410` while the dedicated server installer remains defined on the normal mod installer entry.
+
+The current XML schema is validated by:
+
+```bash
+php Panel/modules/config_games/tests/validate_server_configs.php
+```
+
 ## Recommended Mental Model
 
 Think of the XML system as the capability definition layer:
@@ -102,4 +147,3 @@ game XML
   -> docs links
   -> scheduler and status hints
 ```
-