[Lock] Update table in lock component

[zozs]

The table on the locks documentation does not seem to be consistent with the description for PostgreSqlStore. The table currently says the locks are expiring, while the textual descriptions further down the page says the opposite:

the PostgreSqlStore does not need a table to store locks and does not expire.

and

That means that by using :ref:PostgreSqlStore <lock-store-pgsql> the locks will be automatically released at the end of the session in case the client cannot unlock for any reason.

Proposed fix, modify the table so it says no under the Expiring column for PostgreSqlStore.

[javiereguiluz]

Linus, thanks for fixing this error and thanks for the detailed explanation!

Congrats on your first Symfony Docs contribution 🎉