Add docs for forms.
Add Forms to TOC and topics.
update code example
update menu list
update links
Update PDF and epub to include new form docs.
improve code example
Update retrieving-data-and-resultsets.rst

The link to the query builder is quite important, since the query builder doc page extends this page. But when scrolling over this page, it's not very obvious. It just looks like the examples above are explained here and the link is pretty "hidden". This should help make the link (and it's importance) more clear.
Merge pull request #2160 from oldskool/patch-1

Update retrieving-data-and-resultsets.rst
fix code formating
fix code format
Merge pull request #2152 from cakephp/3.0-form

Add documentation for Form classes