Document providers in Readme markdown files

[DaveRMaltby]

These providers need good documentation and in that documentation different features should have example code.

Notable areas:

• In a transaction, uncommitted INSERT rows will show up in SELECT statements. (Note: This behavior only works for multiple statements of a command that is on the DataReader. See issue In a transaction, uncommitted INSERT rows will show up in SELECT statements #36)
• Built-in functions: LAST_INSERT_ID and ROW_COUNT (Matches equalivent functions provided in MySQL)
• LIMIT keyword