fixed documentation of from<CString> for Rc<CStr>: Arc -> Rc

Author: nurmukhametdaniyar

library/alloc/src/ffi/c_str.rs

@@ -888,7 +888,7 @@ impl From<&CStr> for Arc<CStr> {
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<CString> for Rc<CStr> {
     /// Converts a [`CString`] into an <code>[Rc]<[CStr]></code> by moving the [`CString`]
-    /// data into a new [`Arc`] buffer.
+    /// data into a new [`Rc`] buffer.
     #[inline]
     fn from(s: CString) -> Rc<CStr> {
         let rc: Rc<[u8]> = Rc::from(s.into_inner());