[DOCS] Minor Typo in SELECT docs

[Thomas F . O'Connell]

There is a reference to the "<x-tad-bigger>sql_interitance</x-tad-bigger>" configuration in the 7.4.x docs:

http://www.postgresql.org/docs/7.4/static/sql-select.html

I don't know whether their will be anything beyond 7.4.5, but this would be an easy patch.

-tfo