docs: fix trailing ``` in mod.rs example

[bdura]

A most minor documentation fix.

[marshallpierce]

Thanks! I'll look at the CI issue; it's not related to your change.

[marshallpierce]

Should be fixed upstream now; rebase or merge and it should pass.

[bdura]

I missed you comment, sorry about that! I merged the upstream changes.

[marshallpierce]

Thanks!