Add uninlined_format_args example for {:?}

[AljoschaMeyer]

Before this, you had to guess how to fix a {:?} formatting argument. I have happened to guess {:?var} in the past, got frustrated, and disabled the lint. This additional example would have saved me a bit of trouble.

changelog: [uninlined_format_args]: added an example of how to fix a {:?} parameter.

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[dswij]

Actually, can you leave out the unnecessary commit message here, or change it to be something more descriptive? Thanks!

[AljoschaMeyer]

Sorry, that was autogenerated by github I think. Does the first line only, i.e., "Add uninlined_format_args example for {:?}" work for you?

[AljoschaMeyer]

Okay, force-pushed a shorter commit message. I hope this works =S