Start linking to the new ORM docs instead of the model ones.
Add docs for validate() and validateMany()
Add doc stub for counter cache behavior.
Fix formatting errors.
Start behavior docs.

Include excerpts from existing files.
Update templates for 3.0 book.
Add annoying banner.

I hope it helps minimize the confusion around the docs being very
different than before and incomplete.
Update search index version.
Update search index build script.

* Use the correct index #.
* Use the correct default URL.
Update example so it is relevant
Merge pull request #959 from cakephp/3.0-more-orm-docs

3.0 more orm docs