fix library/std/src/sys_common/wtf8.rs

Co-authored-by: GrigorenkoPV <GrigorenkoPV+github@yandex.ru>

Author: HTGAzureX1212

library/std/src/sys_common/wtf8.rs

@@ -668,7 +668,7 @@ impl Wtf8 {
     /// Lossily converts the string to UTF-8.
     /// Returns a UTF-8 `&str` slice if the contents are well-formed in UTF-8.
     ///
-    /// Surrogates are replaced with `"\u{FFFD}"` (the replacement character “ ”).
+    /// Surrogates are replaced with `"\u{FFFD}"` (the replacement character “�”).
     ///
     /// This only copies the data if necessary (if it contains any surrogate).
     pub fn to_string_lossy(&self) -> Cow<'_, str> {