[1.6.x] Fixed #22368 -- clarified connecting to Oracle DB using service name

Used the official terminology listed in
http://docs.oracle.com/cd/B19306_01/network.102/b14212/glossary.htm#i997309

Thanks michael.cherkasov for the report.

Backport of bfac6bef83 from master
[1.6.x] Fixed #22655 -- Fixed GeoQuerySet doc about strictly_below

The paragraph was a copy of strictly_above.

Backport of 2f43229c2f from master