fix typo in basic_istream

suomesta · suomesta · commit d9fff1aa54f0 · 2025-06-05T20:11:19.000+09:00
diff --git a/reference/istream/basic_istream/op_istream_free.md b/reference/istream/basic_istream/op_istream_free.md
@@ -88,7 +88,7 @@ namespace std {
 
 ## 戻り値
 
-`*this`
+`is`
 
 
 ## 例（文字列）
