Fix rst markers

Author: aisk

Misc/NEWS.d/next/Library/2025-08-31-12-34-02.gh-issue-138205.iHXb1z.rst

@@ -1,2 +1,2 @@
-Removed the :mmap:`~mmap.mmap.resize` method on platforms that don't support the
-underlying syscall, instead of raising a :exec:`SystemError`.
+Removed the :method:`~mmap.mmap.resize` method on platforms that don't support the
+underlying syscall, instead of raising a :exc:`SystemError`.