docs(allocator): add safety constraint for String::from_raw_parts_in

Author: overlookmotel

crates/oxc_allocator/src/string.rs

@@ -212,6 +212,8 @@ impl<'alloc> String<'alloc> {
     /// * The memory at `ptr` needs to have been previously allocated by the same [`Allocator`].
     /// * `length` needs to be less than or equal to `capacity`.
     /// * `capacity` needs to be the correct value.
+    /// * The region of memory starting at `ptr` and spanning `length` bytes must contain a valid
+    ///   UTF-8 string.
     ///
     /// Violating these may cause problems like corrupting the allocator's internal data structures.
     ///
@@ -221,7 +223,6 @@ impl<'alloc> String<'alloc> {
     ///
     /// # Examples
     /// ```
-    /// use std::mem;
     /// use oxc_allocator::{Allocator, String};
     ///
     /// let allocator = Allocator::default();