Screen readers report a field's help text before any errors

[Kyle Bayliss]

From @thibaudcolas:

The fields’ aria-describedby has the help text first, error messages second, while in the template we show the error messages first. I think both should match. I like the idea of having errors first, so the beginning of the field’s description is "Error:". Means we don’t need to additionally have aria-invalid="true".

[Thibaud Colas]

Not strictly required but would be nice to have such a simple fix done from the first release.