Added some more comments.

db_sqlite.go

@@ -95,10 +95,13 @@ func initSQLiteStatements(db *sql.DB) error {
 	return nil
 }
 
+// SQLiteDatabase implements a Guestbook that works with a SQLite DB
+// under the hood.
 type SQLiteDatabase struct {
 	db *sql.DB
 }
 
+// NewSQLiteDB returns an instance of a SQLite Guestbook implementation.
 func NewSQLiteDB(filePath string) (Guestbook, error) {
 	db, err := sql.Open("sqlite3", sqliteDSN(filePath))
 	if err != nil {