Fixed #6765: Changed docs/model-apit.txt to better indicate what's expected of initial SQL files.

    INSERT INTO myapp_person (first_name, last_name) VALUES ('John', 'Lennon');

    INSERT INTO myapp_person (first_name, last_name) VALUES ('Paul', 'McCartney');

Each SQL file, if given, is expected to contain valid SQL. The SQL files are

piped directly into the database after all of the models' table-creation

statements have been executed.

Each SQL file, if given, is expected to contain valid SQL statements

which will insert the desired data (e.g., properly-formatted

``INSERT`` statements separated by semicolons).

The SQL files are read by the ``sqlcustom``, ``sqlreset``, ``sqlall`` and

``reset`` commands in ``manage.py``. Refer to the `manage.py documentation`_