Add messaging about second approvals to merge directly to Mergeable check.

PiperOrigin-RevId: 499605832

.github/mergeable.yml

diff --git a/.github/mergeable.yml b/.github/mergeable.yml
index fdb06d9..ec30a8e 100644
--- a/.github/mergeable.yml
+++ b/.github/mergeable.yml
@@ -10,6 +10,6 @@
             message: 'Pull requests should not be merged directly and should instead
               be handled by Copybara.
 
-              To enable Github merges, add the `mergeable:force-allow` label.
-              This should almost never be used except for releases or as a break glass measure
-              after discussing with the team.'
+              To enable Github merges, add the `mergeable:force-allow` label and get a second 
+              approval. This should almost never be used except for releases or as a break glass 
+              measure after discussing with the team.'