Adding section about SQLite limitation

More information at #300

Better Dapper.Contrib README

- Added an example for the [Table] attribute which was missing.
- Additionally separated things onto separate lines for better
readablility
- Better headings

Brackets around property names in Update & Delete

Modified Update & Delete method to be consistent with Insert by adding brackets around property names

SO30435185; make it clearer if the caller is passing an array (etc) when they should be passing a single object

Conflicts:
	Dapper NET40/SqlMapper.cs

This reverts commit 27abc447.

This reverts commit db942443.