fix(doc/changes): describe fallout from parameterized user attributes

@kha This was an unexpected breakage resulting from #1809.

doc/changes.md

@@ -137,6 +137,8 @@ For more details, see discussion [here](https://github.com/leanprover/lean/pull/
   `⟨h1, h2⟩`. This change is motivated by the previous one. Without it, `and.intro h1 h2` would be
   pretty printed as `{left := h1, right := h2}`.
 
+* User attributes can no longer be set with `set_basic_attribute`.  You need to use `user_attribute.set_param` now.
+
 *API name changes*
 
 * `list.dropn` => `list.drop`