You can use badges to show state of your documentation to your users. The default badge will be pointed at the latest version of a crate. You can use version parameter to show status of documentation for any version you want.

Badge will display in blue if is successfully hosting your crate documentation, and red if building documentation failing.

Example badges for mio crate:

URL Badge
Latest version: mio
Version 0.4.4: mio
Version 0.1.0: mio