Where is the comment commands of add `/hold` or `/hold cancel` when make PR?

When I read this document of Marking Unfinished Pull Requests

  1. You may add the /hold or /hold cancel comment commands

whether there means add /hold or /hold cancel on there?

/hold will add the label do-not-merge/hold. Our CI recognizes this label and will not allow it to merge, even if it meets all other criteria to be merged. It’s used for WIP PRs or often when people want feedback from multiple people with the ability to approve/lgtm a PR.

/hold cancel removes the label, signaling its ready to be reviewed or the pr author is ready to see it merged after getting feedback from multiple groups.