Remove Qiskit Terra 0.25 from release_notes.rst (#11436)

* Remove Qiskit Terra 0.25 from release_notes.rst

* Review feedback: use a comment

docs/release_notes.rst

@@ -4,8 +4,12 @@
 Release Notes
 =============
 
-This page contains the release notes for Qiskit, starting from the point at which the legacy
-"elements" structure was completely removed.
+This page contains the release notes for Qiskit, starting from Qiskit 0.45, the first time that Qiskit and Qiskit Terra had the same versions.
+
+..
+    These release notes get converted into Markdown files via the infrastructure at https://github.com/Qiskit/documentation, which then gets deployed to https://docs.quantum.ibm.com/api/qiskit/release-notes. Changes to these release notes will update those release notes the next time the API docs are generated.
+
+    To change release notes prior to Qiskit 0.45, update the Qiskit/documentation repository directly.
 
 .. release-notes::
    :earliest-version: 0.45.0rc1
@@ -18,7 +22,3 @@ This page contains the release notes for Qiskit, starting from the point at whic
 .. release-notes::
    :earliest-version: 0.45.0
    :branch: stable/0.45
-
-.. release-notes::
-   :earliest-version: 0.25.0
-   :branch: stable/0.25