How is the "mirrored from" annotation added to a mirrored repo?

When checking some official mirrors on GitHub, some repos have the “mirrored from” annotation, for example shows “mirrored from” below the repo name “aosp-mirror/platform_frameworks_base”.

Some mirrored repo on the other hand, like the Qt mirrors and KDE mirrors, does not. (e.g.

Is it something that the repo owner have to ask GitHub staffs to add manually?

That “mirrored from” notation indicates that GitHub syncs with the official repo periodically. While that is something we used to occasionally set up for repositories on our end, we now recommend using a post-receive hook to automatically mirror the repo. The advantage of that is the mirror will always be up-to-date instead of being behind the official repo until our sync job runs. You can read more about mirroring on GitHub here:

@cmrberry I know that this is an old thread, but just wanted to confirm: there is no way to get the “mirror” symbol or annotation when a user manually sets up a mirror from a post-receive hook on the original repository?