Section I - 2.9: Use SELECT to confirm set of rows before DELETE

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/14/tutorial-delete.html
Description:

Since this tutorial section is coined at beginners, I think it could be
useful to tip users about the possibility to use a SELECT statement with the
exact same qualification(s) as the DELETE statement they're planning to run
to see which rows are about to be deleted, to avoid unintended deletion of
rows. I suggest something like this:

...
Without a qualification, DELETE will remove all rows from the given table,
leaving it empty. The system will not request confirmation before doing
this!

You can check which rows will be deleted by any DELETE statement on the
form:
```DELETE FROM tablename ... <qualificaton> ...```
by rewriting it into a corresponding SELECT statement:
```SELECT * FROM tablename ... <qualification> ...```

This is my first attempt at contributing to the community, so please be
nice. :)