Обсуждение: pgsql: Doc: Fix various inconsistencies

Doc: Fix various inconsistencies

This fixes multiple areas of the documentation:
- COPY for its past compatibility section.
- SET ROLE mentioning INHERITS instead of INHERIT
- PREPARE referring to stmt_name, that is not present.
- Extension documentation about format name with upgrade scripts.

Backpatch down to 9.4 for the relevant parts.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/bf95233a-9943-b341-e2ff-a860c28af481@gmail.com
Backpatch-through: 9.4

Branch
------
REL_10_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/c0e5df9b2595eef89a756e76d742fc06b3469524

Modified Files
--------------
doc/src/sgml/extend.sgml       |  2 +-
doc/src/sgml/ref/copy.sgml     | 20 ++++++++++----------
doc/src/sgml/ref/set_role.sgml |  2 +-
3 files changed, 12 insertions(+), 12 deletions(-)