pgsql: Fix documentation of information_schema.element_types

Fix documentation of information_schema.element_types

The documentation of the columns collection_type_identifier and
dtd_identifier was wrong.  This effectively reverts commits
8e1ccad51901e83916dae297cd9afa450957a36c and
57352df66d3a0885899d39c04c067e63c7c0ba30 and updates the name
array_type_identifier (the name in SQL:1999) to
collection_type_identifier.

closes bug #5926

Branch
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REL8_3_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/302e4e6f3b5f5e03162f11c8a074d337cd11acf7

Modified Files
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doc/src/sgml/information_schema.sgml |   16 +++++++++++++---
1 files changed, 13 insertions(+), 3 deletions(-)