Add a post about the mailing list move

In support of guacsec/governance#6

Signed-off-by: Ben Cotton <ben@kusari.dev>

Author: funnelfiasco

content/blog/2024-06-21-mailing-list-move.md

@@ -0,0 +1,17 @@
+---
+title: GUAC mailing lists moving to OpenSSF
+layout: post
+authors: ["Ben Cotton"]
+date: 2024-06-21
+include_footer: true
+---
+
+The GUAC mailing lists are moving from Google Groups to the OpenSSF list server.
+Join [GUAC@lists.openssf.org](https://lists.openssf.org/g/GUAC) to continue receiving updates and participating in the conversation.
+This list is open for all community discussion of GUAC.
+The Google Groups list will enter read-only mode after the July 18 GUAC Community Meeting.
+
+The GUAC maintainer list is also moving.
+Use [GUAC-maintainers@lists.openssf.org](https://lists.openssf.org/g/GUAC-Maintainers) to report security issues or other confidential concerns to the maintainers.
+
+We look forward to chatting with you on the [mailing list](https://lists.openssf.org/g/GUAC) and in [#GUAC on the OpenSSF Slack](https://openssf.slack.com/archives/C03U677QD46).