Clarify the wording on an infer_schema error message (#1057)
Clarify the wording on an infer_schema error message (#1057)

This error message could be interpreted to be saying that when the
dotenv feature is enabled, the string must begin with `dotenv:`. I
believe the new wording clarifies that the issue is that the dotenv
feature has not been enabled in the first place.
diesel-rs/diesel,sgrif/diesel,sgrif/diesel,diesel-rs/diesel