Follow our own recommendations in the examples

[vickenty]

Remove exclamation marks from the the example error descriptions:

The description [...] should not contain newlines or sentence-ending punctuation

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @alexcrichton (or someone else) soon.

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[bluss]

@vickenty Thanks. I was just looking at this. Maybe it should also show somehow that Display can use formatting/interpolation when description does not, if there is a nice way to do that? It is a common question.

[steveklabnik]

@bors: r+ rollup

Thank you!

(I agree that @bluss 's suggestions sound good as well, if you or anyone else wants to send in another PR for that.)

[bors]

📌 Commit a3ce398 has been approved by steveklabnik