Proposal: prefer `%q` to format strings over `%s`

[yuxincs]

Note All credit goes to @abhinav

I learned this from one of @abhinav's amazing talks, and thought we could probably add this practice to this doc.

Whenever formatting messages that contain a string component via fmt, prefer %q instead of %s. This will wrap the specified string in quotes, helping it stand out from the rest of the error message. More importantly, if the string is empty, it will provide a more helpful error message.

Bad	Good
fmt.Errrof("file %s not found", filename) // Prints the following: // file myfile.go not found // // Or if the string is empty: // file not found	fmt.Errrof("file %q not found", filename) // Prints the following: // file "myfile.go" not found // // Or if the string is empty: // file "" not found