mysql-native: preview3 (docs)

[Nick Sabalausky via Digitalmars-d-announce]

https://github.com/Abscissa/mysql-native-experimental
Tag: v0.2.0-preview3

Just a few doc updates this time:

- Docs now include the `mysql.db.MysqlDB` to `mysql.pool.MySqlPool` 
change from preview2
- Clarified "Prepared" vs "PreparedImpl"
- Clarified "exec" vs "query"
- Rewrite the docs for ResultSet and ResultRange.

New docs:
http://semitwist.com/mysql-native-docs/v0.2.0-preview3