docs(release-notes): add markers for contributors and changelog sections

- Add machine-readable <!-- BEGIN/END contributors --> markers to the
- release notes to enable automated contributor extraction
- Add <!-- BEGIN/END changelog --> markers around v1.18.2, v1.18.1 and
- v1.18.0 sections so the release generator can parse changelogs

Signed-off-by: Richard Wall <[email protected]>

Author: wallrj-cyberark

content/docs/releases/release-notes/release-notes-1.18.md

@@ -164,7 +164,7 @@ Read [Annotated Ingress resource: Copy annotations to the Certificate](../../usa
 As always, we'd like to thank all of the community members who helped in this release cycle, including all below who merged a PR and anyone that helped by commenting on issues, testing, or getting involved in cert-manager meetings. We're lucky to have you involved.
 
 A special thanks to:
-
+<!-- BEGIN contributors -->
 - [`@terinjokes`](https://github.com/terinjokes)
 - [`@solidDoWant`](https://github.com/solidDoWant)
 - [`@k0da`](https://github.com/k0da)
@@ -182,6 +182,7 @@ A special thanks to:
 - [`@tobiasbp`](https://github.com/tobiasbp)
 - [`@vehagn`](https://github.com/vehagn)
 - [`@cuinix`](https://github.com/cuinix)
+<!-- END contributors -->
 
 for their contributions, comments and support!
 
@@ -202,6 +203,7 @@ And finally, thanks to the cert-manager steering committee for their feedback in
 - [@TrilokGeer](https://github.com/TrilokGeer)
 
 
+<!-- BEGIN changelog v1.18.2 -->
 ## `v1.18.2`
 
 We fixed a bug in the CSR's name constraints construction (only applies if you have enabled the `NameConstraints` feature gate).
@@ -217,6 +219,8 @@ Changes since `v1.18.1`:
 [#7833]: https://github.com/cert-manager/cert-manager/issues/7833
 [#7837]: https://github.com/cert-manager/cert-manager/issues/7837
 
+<!-- END changelog v1.18.2 -->
+<!-- BEGIN changelog v1.18.1 -->
 ## `v1.18.1`
 
 We have added a new feature gate `ACMEHTTP01IngressPathTypeExact`, to allow
@@ -244,6 +248,8 @@ Changes since `v1.18.0`:
 
 - Use the latest version of ingress-nginx in E2E tests to ensure compatibility ([`#7807`](https://github.com/cert-manager/cert-manager/pull/7807), [`@wallrj`](https://github.com/wallrj))
 
+<!-- END changelog v1.18.1 -->
+<!-- BEGIN changelog v1.18.0 -->
 ## `v1.18.0`
 
 Changes since `v1.17.2`:
@@ -297,3 +303,4 @@ Changes since `v1.17.2`:
 - Update kind images to include the Kubernetes 1.33 node image ([`#7787`](https://github.com/cert-manager/cert-manager/pull/7787), [`@wallrj`](https://github.com/wallrj))
 - Upgrade Go to `v1.24.4` ([`#7785`](https://github.com/cert-manager/cert-manager/pull/7785), [`@wallrj`](https://github.com/wallrj))
 - Use `slices.Contains` to simplify code ([`#7753`](https://github.com/cert-manager/cert-manager/pull/7753), [`@cuinix`](https://github.com/cuinix))
+<!-- END changelog v1.18.0 -->