pgsql: Doc: Fix various typos

Doc: Fix various typos

All those fixes are already included on HEAD thanks to for example
c96581a and 66bde49, and have gone missing on back-branches.

Author: Alexander Lakhin, Liudmila Mantrova
Discussion: /messages/by-id/CAEkD-mDJHV3bhgezu3MUafJLoAKsOOT86+wHukKU8_NeiJYhLQ@mail.gmail.com
Backpatch-through: 9.4

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/15ae1a31b433cff340b14a11268a0c9746e4a19d

Modified Files
--------------
doc/src/sgml/custom-scan.sgml | 5 +----
doc/src/sgml/ecpg.sgml | 2 +-
doc/src/sgml/func.sgml | 4 ++--
doc/src/sgml/gist.sgml | 8 ++++----
doc/src/sgml/libpq.sgml | 2 +-
doc/src/sgml/plpgsql.sgml | 4 ++--
doc/src/sgml/problems.sgml | 2 +-
doc/src/sgml/ref/create_aggregate.sgml | 2 +-
doc/src/sgml/ref/set_role.sgml | 2 +-
doc/src/sgml/sources.sgml | 2 +-
doc/src/sgml/sslinfo.sgml | 2 +-
doc/src/sgml/xplang.sgml | 2 +-
12 files changed, 17 insertions(+), 20 deletions(-)