[Custom DC] Add enable mcp and search scope vars to sample env file (#5989)

Author: keyurva

custom_dc/env.list.sample

@@ -44,6 +44,14 @@ REDIS_HOST=
 # (Optional) Secret token to authorize users to perform /admin page operations.
 ADMIN_SECRET=
 
+### MCP parameters ###
+
+# (Optional) If true, MCP server will be started. Default: true.
+# ENABLE_MCP=true
+# (Optional) Search scope for querying indicators (variables and topics).
+# Options: "base_and_custom" (default), "custom_only"
+# DC_SEARCH_SCOPE=base_and_custom
+
 ### Google Analytics ###
 
 # (Optional) Set to your Google Tag ID to enable Google Analytics. See https://support.google.com/analytics/answer/9539598