add SLACK_BOT_USES_ONLY_ENV_VARS_FOR_SOME_OPTIONS

src/server/service/config-loader.js

@@ -416,6 +416,12 @@ const ENV_VAR_NAME_TO_CONFIG_INFO = {
     type:    TYPES.STRING,
     default: null,
   },
+  SLACK_BOT_USES_ONLY_ENV_VARS_FOR_SOME_OPTIONS: {
+    ns:      'crowi',
+    key:     'security:slack-signing-secret:useOnlyEnvVarsForSomeOptions',
+    type:    TYPES.BOOLEAN,
+    default: false,
+  },
 };
 
 class ConfigLoader {