Add inputTooShortText label.

[kompot]

No description provided.

[JedWatson]

Do you think enterSearchText or noInputText would be clearer for this prop name? inputTooShort implies that there's a minimum length setting to me.

[kompot]

Well,
actually I think that minimum length setting should be a mandatory setting (defaulting to 1 probably).

I can change it but creating a ticket for adding mandatory minimum input length seems also reasonable.

Up to you to decide.

[JedWatson]

I've implemented this as searchPromptText because I think that's the clearest explanation for the text string itself. I also agree we could add a minimum length setting, but that requires some deeper thought because of the interaction with the autoloading of the default set of options.

The output is also dependent on asyncOptions being set, because otherwise in a situation where there are no options available (and no more may be loaded) it will say "Type to search..." which is not, I don't think, the correct behaviour.

Let me know if you think this should be tweaked.

[JedWatson]

p.s. although I made the change directly rather than merging your PR, you got credit for this in the changelog :)