Fix some formatting in the v2.8.0 changelog (#3339)

[skipci]

docs/changelog.rst

@@ -53,9 +53,10 @@ New features:
   `#3293 <https://github.com/pybind/pybind11/pull/3293>`_
 
 * Improve the classes generated by ``bind_map``: `#3310 <https://github.com/pybind/pybind11/pull/3310>`_
-    * Change ``.items`` from an iterator to a dictionary view.
-    * Add ``.keys`` and ``.values`` (both dictionary views).
-    * Allow ``__contains__`` to take any object.
+
+  * Change ``.items`` from an iterator to a dictionary view.
+  * Add ``.keys`` and ``.values`` (both dictionary views).
+  * Allow ``__contains__`` to take any object.
 
 * ``pybind11::custom_type_setup`` was added, for customizing the
   ``PyHeapTypeObject`` corresponding to a class, which may be useful for