docs(application): drop a versionchanged note for a feature added in the same release

An inline review comment on #2451 flagged this and was never acted
on before the PR merged: the DTLS module's reassembly support has no
prior version to have changed from, since the whole module is new in
1.6.0. Drop the redundant versionchanged block; the reassembly
behavior is already described in the module's own Known Limitations
prose.

Author: JarryShaw

pcapkit/protocols/application/dtls.py

@@ -35,12 +35,6 @@
 
 .. versionadded:: 1.6.0
 
-.. versionchanged:: 1.6.0
-
-   :meth:`read` reassembles a fragmented handshake message and decodes it,
-   given a :class:`~pcapkit.foundation.reassembly.dtls.DTLS` engine via its
-   new ``reassembly`` argument (:issue:`2440`).
-
 """
 from typing import TYPE_CHECKING, cast