Corrected the documented intent of the HKDFExpand.derive() function so that it clearly states only expand is performed, and not extract and expand. (#12248)

Author: Torxed

docs/hazmat/primitives/key-derivation-functions.rst

@@ -665,8 +665,8 @@ HKDF
                                                           called more than
                                                           once.
 
-        Derives a new key from the input key material by performing both the
-        extract and expand operations.
+        Derives a new key from the input key material by only performing the
+        expand operation.
 
     .. method:: verify(key_material, expected_key)