doc: dev: Minor change.

doc/dev/documentation.org

@@ -369,6 +369,7 @@ of Bar (Listing [[sql-bar]] and [[sql-foo]]).
             CREATE TABLE bar (
               id INTEGER NOT NULL PRIMARY KEY,
               x INTEGER NOT NULL,
+              y INTEGER NOT NULL,
               foo_id INTEGER NOT NULL,
               FOREIGN KEY(foo_id) REFERENCES foo(id),
             )""")