Description for feed full text/summary settings

[JarretC]

I've come across a few support questions in the forums where users go into the Settings->Reading menu and assume that modifying the 'For each article in a feed, show' options also controls how the content will be displayed on the theme itself. While the label is specific not everybody may even know what a feed is.

Suggesting adding a description below the options that explain a bit further

[SergeyBiryukov]

Thanks for the ticket! Adding a description there would indeed be helpful.

For feeds only, it is up to your theme to choose how content is displayed.

I think the wording could be improved a bit. Some site authors might be wondering, "why is it not up to me"? :)

Maybe something like this?

This option applies to feeds only. How content is displayed on your site depends on the theme you use.

Marking as needs-copy-review for @marybaum :)