Moving `newEntity` docs to the bottoms of the document.

The task is tangential to what you want to do with tables and is probably
something that will need to be explained again in teh controller docs
Adding some docs for patchEntity
Adding a couple of paragraphs for patchEntities
Fixed some typos and other things
Merge pull request #1130 from cakephp/3.0-patch-entity

3.0 patch entity