doc: indent code fence under list item

PR-URL: #29822
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: nschonni

doc/guides/security_release_process.md

@@ -70,9 +70,9 @@ a security release.
   * In the docker-node repository run the
     [generate-stackbrew-library.sh]( https://github.com/nodejs/docker-node/blob/master/generate-stackbrew-library.sh)
     script and replace official-images/library/node with the output generated.
-```shell
-$ ./generate-stackbrew-library.sh > .../official-images/library/node
-```
+    ```console
+    $ ./generate-stackbrew-library.sh > .../official-images/library/node
+    ```
   * Open a PR with the changes to official-images/library/node making sure to
     @mention the official images.
     [maintainers](https://github.com/docker-library/official-images/blob/master/MAINTAINERS).