Update merge-queue gated feature for GHES 3.12 (#31946)

Co-authored-by: Isaac Brown <[email protected]>

Author: willsmythe

data/reusables/gated-features/merge-queue.md

@@ -1 +1,5 @@
+{% ifversion fpt or ghec %}
 Pull request merge queues are available in any public repository owned by an organization, or in private repositories owned by organizations using {% data variables.product.prodname_ghe_cloud %}. {% data reusables.gated-features.more-info %}
+{% elsif ghes %}
+Pull request merge queues are available in any organization-owned repository on {% data variables.product.product_name %}.
+{% endif %}