Instead of just having a button, what about making this button go to a new page which would contain a kind of information summary with the following information:
- Crate name
- Version which would be rebuild
- A confirmation button
If the user is not logged in, it would (instead of the confirmation button) contain a message mentioning that only the crate owner(s) can trigger a documentation rebuild.
It would also allows docs.rs to directly link to this page.
If it sounds ok to you, I can send a PR to implement it.