Fix markup in NEWS file.

Author: nascheme

Misc/NEWS.d/next/Core_and_Builtins/2026-06-24-15-52-19.gh-issue-151593.bWdDi1.rst

@@ -1,3 +1,3 @@
-Fix deadlock in :c:func:`insert_split_key`.  We must not acquire other locks
+Fix deadlock in ``insert_split_key()``.  We must not acquire other locks
 while holding the ``LOCK_KEYS()`` mutex.  This issue is fixed by calling
-:c:func:`PyType_Modifed` after releasing the mutex.
+:c:func:`PyType_Modified` after releasing the mutex.