pgsql: Copy-edit the docs changes of OWNER TO CURRENT/SESSION_USER addi

Copy-edit the docs changes of OWNER TO CURRENT/SESSION_USER additions.

Commit 31eae602 added new syntax to many DDL commands to use CURRENT_USER
or SESSION_USER instead of role name in ALTER ... OWNER TO, but because
of a misplaced '{', the syntax in the docs implied that the syntax was
"ALTER ... CURRENT_USER", instead of "ALTER ... OWNER TO CURRENT_USER".
Fix that, and also the funny indentation in some of the modified syntax
blurps.

Branch
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REL9_5_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/ebe8bcd94e7191025e0309718284983891a89064

Modified Files
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doc/src/sgml/ref/alter_large_object.sgml |    2 +-
doc/src/sgml/ref/alter_opclass.sgml      |    6 +++---
doc/src/sgml/ref/alter_operator.sgml     |    4 ++--
doc/src/sgml/ref/alter_opfamily.sgml     |    6 +++---
4 files changed, 9 insertions(+), 9 deletions(-)