Add documentation

database.go

@@ -5,10 +5,15 @@ import (
 	"zombiezen.com/go/sqlite"
 )
 
+// Db holds a connection to a SQLite database.
 type Db struct {
 	Db *sqlite.Conn
 }
 
+// OpenDb opens a new connection to a SQLite database.
+// The databaseSource specifies the database to use. Set it to `:memory:` to use
+// an in-memory database.
+// Any database that was successfully opened should afterwards be closed using Db.Close
 func OpenDb(databaseSource string) (*Db, error) {
 	conn, err := sqlite.OpenConn(databaseSource)
 	if err != nil {
@@ -17,10 +22,13 @@ func OpenDb(databaseSource string) (*Db, error) {
 	return &Db{Db: conn}, nil
 }
 
+// Close closes the database.
 func (d *Db) Close() error {
 	return d.Db.Close()
 }
 
+// MustClose closes the database. If an error occurs, it panics instead of
+// returning the error.
 func (d *Db) MustClose() {
 	err := d.Close()
 	if err != nil {