spelling: expressions

Signed-off-by: Josh Soref <2119212+jsoref@users.noreply.github.com>

Author: jsoref

cpp/ql/lib/semmle/code/cpp/valuenumbering/HashCons.qll

@@ -104,7 +104,7 @@ private newtype HC_Alloc =
   HC_HasAlloc(HashCons hc) { mk_HasAlloc(hc, _) }
 
 /**
- * Used to implement optional extent expression on `new[]` exprtessions
+ * Used to implement optional extent expression on `new[]` expressions
  */
 private newtype HC_Extent =
   HC_NoExtent() or