Rollup merge of #129963 - rjooske:fix/inaccurate_to_string_lossy_doc, r=workingjubilee

Inaccurate `{Path,OsStr}::to_string_lossy()` documentation

The documentation of `Path::to_string_lossy()` and `OsStr::to_string_lossy()` says the following:
> Any non-Unicode sequences are replaced with `U+FFFD REPLACEMENT CHARACTER`

which didn't immediately make sense to me. ("non-Unicode sequences"?)
Since both `to_string_lossy` functions eventually become just a call to `String::from_utf8_lossy`, I believe the documentation meant to say:
> Any *non-UTF-8* sequences are replaced with `U+FFFD REPLACEMENT CHARACTER`

This PR corrects this mistake in the documentation.

For the record, a similar quote can be found in the documentation of `String::from_utf8_lossy`:
> ... During this conversion, `from_utf8_lossy()` will replace any invalid UTF-8 sequences with `U+FFFD REPLACEMENT CHARACTER`, ...

library/std/src/ffi/os_str.rs

@@ -852,7 +852,7 @@ pub fn to_str(&self) -> Option<&str> {
 
     /// Converts an `OsStr` to a <code>[Cow]<[str]></code>.
     ///
-    /// Any non-Unicode sequences are replaced with
+    /// Any non-UTF-8 sequences are replaced with
     /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD].
     ///
     /// [U+FFFD]: crate::char::REPLACEMENT_CHARACTER

library/std/src/path.rs

@@ -2200,7 +2200,7 @@ pub fn to_str(&self) -> Option<&str> {
 
     /// Converts a `Path` to a [`Cow<str>`].
     ///
-    /// Any non-Unicode sequences are replaced with
+    /// Any non-UTF-8 sequences are replaced with
     /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD].
     ///
     /// [U+FFFD]: super::char::REPLACEMENT_CHARACTER