pgsql: doc: show direction is optional in FETCH/MOVE's FROM/IN syntax

doc: show direction is optional in FETCH/MOVE's FROM/IN syntax

It used to show direction was required for FROM/IN.

Reported-by: Rob <rirans@comcast.net>

Discussion: /messages/by-id/20211015165248.isqjceyilelhnu3k@localhost

Author: Rob <rirans@comcast.net>

Backpatch-through: 10

Branch
------
REL_15_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/27e8fc4bcc33e94cd0016b81464bbb7b13d47775

Modified Files
--------------
doc/src/sgml/ref/fetch.sgml | 5 +++--
doc/src/sgml/ref/move.sgml | 5 +++--
2 files changed, 6 insertions(+), 4 deletions(-)