Tidy up HTML

Remove error <span> as FormIt outputs those anyway, move button inside
fieldset since it is logically associated with the form fields above it.
Update SS form HTML

Add fieldset and legend for completeness
No results from search chunk
SimpleSearch pagination chunks
Paging requires parent UL element

Since my SS pagination chunks are set as LI elements
SS custom driver.

Found somewhere on the MODX forums, and cannot find the article now!
Collection landing page template tweaks

Add article element around the content, as per most other templates.
Remove UL element around page.nav as this outputs a DIV with a UL
inside by default.
Re-indent to 4 spaces
Remove required & replace with global placeholders

For ClientConfig configuring of the Contact form
Update README to reflect new placeholders