Fix some txdb comment typos (#13059)

.changeset/spotty-cooks-think.md

@@ -0,0 +1,5 @@
+---
+"chainlink": patch
+---
+
+#internal fix txdb documentation typos

core/internal/testutils/pgtest/txdb.go

@@ -74,8 +74,8 @@ var _ driver.Conn = &conn{}
 var _ driver.Validator = &conn{}
 var _ driver.SessionResetter = &conn{}
 
-// txDriver is an sql driver which runs on single transaction
-// when the Close is called, transaction is rolled back
+// txDriver is an sql driver which runs on a single transaction.
+// When `Close` is called, transaction is rolled back.
 type txDriver struct {
 	sync.Mutex
 	db    *sql.DB
@@ -110,8 +110,8 @@ func (d *txDriver) Open(dsn string) (driver.Conn, error) {
 	return c, nil
 }
 
-// deleteConn is called by connection when it is closed
-// It also auto-closes the DB when the last checked out connection is closed
+// deleteConn is called by a connection when it is closed via the `close` method.
+// It also auto-closes the DB when the last checked out connection is closed.
 func (d *txDriver) deleteConn(c *conn) error {
 	// must lock here to avoid racing with Open
 	d.Lock()