pgsql: Doc: Fix various typos - Mailing list pgsql-committers

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: https://postgr.es/m/CAEkD-mDJHV3bhgezu3MUafJLoAKsOOT86+wHukKU8_NeiJYhLQ@mail.gmail.com
Backpatch-through: 9.4

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/3399b345f1d4047b7c2777946bdd05b1938ed6d1

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(-)