Add HelperText to form elements documentation

[amandaespinosa27]

When user search for the error input, we should display the error cases with the helptext when filled.

In my personal experience, I didn't know the helptext was called like that and I thought it didn't exist.

[lloydaf]

Hi @amandaespinosa27 can you provide some screenshots or some other way to understand the issue better?

[dornelasnelson]

-> Add a HelperText documentation to the form elements within wave