proposal: recommend fmt.Errorf

[albertyw]

Go 1.26 has this in its changelog:

For unformatted strings, fmt.Errorf("x") now allocates less and generally matches the allocations for errors.New("x").

Source: https://go.dev/doc/go1.26#fmtpkgfmt

This probably requires some benchmarking, but should this mean https://github.com/uber-go/guide/blob/master/src/error-type.md should be updated to generally recommend fmt.Errorf for all cases for consistency instead of the current "use fmt.Errorf iff for dynamic error messages"?