Allow for more control over formatting of prefix and postfix

[bobdenotter]

Additional change to #1796

    fields:
        title:
            type: text
            class: large
            required: true
            pattern: ".{2,255}" # see: http://html5pattern.com/
            error: "The Title field is required, and must contain at least 2 characters"
            placeholder: "Placeholder for the title"
            group: Text
            postfix: |
                This is an example of a longer "postfix". Simple text is capped at a reasonable width
                to enhance legibility. Necessitatibus dolor corrupti assumenda placeat quia occati
                aut. Facere porro placeat molestiae fuga. Laboriosam et asperiores atque impedit
                dolorem dicta aut. Harum inventore ipsa voluptas consectetur quaerat eius ad.
                <div class="alert alert-secondary" role="alert"><strong>Tip:</strong> You can even
                use HTML in a prefix! Note that this one does take the full available width.</div>

[I-Valchev]

Awesome tip! Love it.

👍