Since there's already a whole seperate guide dedicated to Formhelpers,
there is no need to duplicate them in the ActionView Helpers guide.
We can link to the FormHelpers guide instead.
The `:include_blank` option of various `<select>`-related helpers causes
an `<option>` element with no content to be rendered. However, the
[HTML spec] says that unless an `<option>` element has a `label`
attribute (which must be non-empty), its content must be "Text that is
not inter-element whitespace."
In #24923, this issue was addressed for `select_tag` by adding a `label`
attribute to the `<option>`. This commit addresses the issue in the
same manner for `FormBuilder#select` and various date / time select
helpers.
[HTML spec]: https://html.spec.whatwg.org/multipage/form-elements.html#the-option-element
The ActionView Overview guide is currently a Work In Progress (WIP)
because, it seems, not all ActionView helpers are listed. As it's also
one of the largest guides, we can move the helpers to a seperate guide.
This allows us to remove the WIP status from the ActionView Overview
guide and reduce its size.
