Changelog

• 5a87a53 Fix README.md
• d1e4165 Merge pull request #31 from sonatard/sql-doc
• 38efa7c Update sql doc
• 127ded2 Merge pull request #32 from sonatard/sql-fix
• 4c24501 Remove Tx.Ping
• 6e0f6bb Merge pull request #29 from sonatard/sql
• 01a323d Support database/sql package
• f63c7c7 Merge pull request #30 from sonatard/fix-doc
• d73a5f9 update README for v0.2.0