fix docs for machine_list_filename param (#3863)

docs/Parameters.rst

@@ -1149,6 +1149,8 @@ Network Parameters
 
    -  each line contains one IP and one port for one machine. The format is ``ip port`` (space as a separator)
 
+   -  **Note**: can be used only in CLI version
+
 -  ``machines`` :raw-html:`<a id="machines" title="Permalink to this parameter" href="#machines">&#x1F517;&#xFE0E;</a>`, default = ``""``, type = string, aliases: ``workers``, ``nodes``
 
    -  list of machines in the following format: ``ip1:port1,ip2:port2``

include/LightGBM/config.h

@@ -976,6 +976,7 @@ struct Config {
   // alias = machine_list_file, machine_list, mlist
   // desc = path of file that lists machines for this parallel learning application
   // desc = each line contains one IP and one port for one machine. The format is ``ip port`` (space as a separator)
+  // desc = **Note**: can be used only in CLI version
   std::string machine_list_filename = "";
 
   // alias = workers, nodes

python-package/lightgbm/basic.py

@@ -299,10 +299,6 @@ class _ConfigAliases:
                "local_listen_port": {"local_listen_port",
                                      "local_port",
                                      "port"},
-               "machine_list_filename": {"machine_list_filename",
-                                         "machine_list_file",
-                                         "machine_list",
-                                         "mlist"},
                "machines": {"machines",
                             "workers",
                             "nodes"},

python-package/lightgbm/dask.py

@@ -233,10 +233,9 @@ def _train(client, data, label, params, model_factory, sample_weight=None, group
 
     # Some passed-in parameters can be removed:
     #   * 'machines': constructed automatically from Dask worker list
-    #   * 'machine_list_filename': not relevant for the Dask interface
     #   * 'num_machines': set automatically from Dask worker list
     #   * 'num_threads': overridden to match nthreads on each Dask process
-    for param_alias in _ConfigAliases.get('machines', 'machine_list_filename', 'num_machines', 'num_threads'):
+    for param_alias in _ConfigAliases.get('machines', 'num_machines', 'num_threads'):
         params.pop(param_alias, None)
 
     # Split arrays/dataframes into parts. Arrange parts into dicts to enforce co-locality