fix: change permission level for instance listing to visitor and making sure all instances could be listed for all users

docs/api.md

@@ -1234,7 +1234,7 @@ X-Timestamp: 1704067200000
 **Endpoint:** `/frpcAct/proxyMgr/list`  
 **Method:** GET  
 **Auth Required:** Yes (token)  
-**Permission Level:** None (any permission level)
+**Permission Level:** Visitor
 
 Retrieve a list of all proxy configurations for a specific frpc instance. The proxy configurations are read from the instance's config file.
 
@@ -1314,7 +1314,7 @@ X-Timestamp: 1704067200000
 **Endpoint:** `/frpcAct/instanceMgr/list`  
 **Method:** GET  
 **Auth Required:** Yes (token)  
-**Permission Level:** Admin
+**Permission Level:** Visitor
 
 Retrieve a list of all frpc instances on the server.
 
@@ -1363,7 +1363,7 @@ X-Timestamp: 1704067200000
 **Auth Required:** Yes (token)  
 **Permission Level:** Visitor
 
-Retrieve information about a specific frpc instance. Returns different information based on user permission level.
+Retrieve information about a specific frpc instance.
 
 **Request Headers:**
 ```