rename extract_docstring.py -> symbol_extractor.py (#2495)

Author: sneaxiy

pkg/attribute/attribute.go

@@ -227,7 +227,7 @@ var XGBoostObjectiveDocs map[string]string
 
 // ExtractDocString extracts parameter documents of Python modules from doc strings
 func ExtractDocString(module ...string) {
-	cmd := exec.Command("python", "-uc", fmt.Sprintf("__import__('extract_docstring').print_param_doc('%s')", strings.Join(module, "', '")))
+	cmd := exec.Command("python", "-uc", fmt.Sprintf("__import__('symbol_extractor').print_param_doc('%s')", strings.Join(module, "', '")))
 	output, e := cmd.CombinedOutput()
 	if e != nil {
 		log.Println("ExtractDocString failed: ", e, string(output))

pkg/attribute/model_parameters.go

@@ -117,7 +117,7 @@ def print_param_doc(*modules):
     param_doc['xgboost.dart'] = param_doc['xgboost.gbtree']
 
     print(
-        '// Code generated by python extract_docstring.py > model_parameters.go. DO NOT EDIT.'
+        '// Code generated by python symbol_extractor.py > model_parameters.go. DO NOT EDIT.'
     )
     print()
     print('package attribute')