Rollup merge of rust-lang#140359 - DiuDiu777:str-fix, r=Noratrieb

specify explicit safety guidance for from_utf8_unchecked

The PR addresses missing safety guidelines in two APIs by adding explicit text to the cross-linked reference.

Author: ChrisDenton

library/core/src/str/converts.rs

@@ -178,7 +178,7 @@ pub const unsafe fn from_utf8_unchecked(v: &[u8]) -> &str {
 /// Converts a slice of bytes to a string slice without checking
 /// that the string contains valid UTF-8; mutable version.
 ///
-/// See the immutable version, [`from_utf8_unchecked()`] for more information.
+/// See the immutable version, [`from_utf8_unchecked()`] for documentation and safety requirements.
 ///
 /// # Examples
 ///

library/core/src/str/mod.rs

@@ -306,7 +306,7 @@ impl str {
     /// Converts a slice of bytes to a string slice without checking
     /// that the string contains valid UTF-8; mutable version.
     ///
-    /// See the immutable version, [`from_utf8_unchecked()`] for more information.
+    /// See the immutable version, [`from_utf8_unchecked()`] for documentation and safety requirements.
     ///
     /// # Examples
     ///