Fix typo

compiler/rustc_data_structures/src/sharded.rs

@@ -185,7 +185,7 @@ pub fn get_or_insert_with(&self, key: K, default: impl FnOnce() -> V) -> V
 
     /// Insert value into the [`ShardedHashMap`] with unique key.
     ///
-    /// Checks uniqness if debug_assertions enabled.
+    /// Checks uniqueness if debug_assertions enabled.
     #[inline]
     pub fn insert_unique(&self, key: K, value: V) {
         let hash = make_hash(&key);