pgsql: Doc: fix oversights in "Client/Server Character Set Conversions"

Doc: fix oversights in "Client/Server Character Set Conversions" table.

This table claimed that JOHAB could be used as a server encoding, which
was true originally but hasn't been true since 8.3. It also lacked
entries for EUC_JIS_2004 and SHIFT_JIS_2004.

JOHAB problem noted by Lars Kanis, the others by me.

Discussion: /messages/by-id/c0f514a1-b7a9-b9ea-1c02-c34aead56c06@greiz-reinsdorf.de

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/3099eec7468f081d638be25475f2c5b43b7d1f88

Modified Files
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doc/src/sgml/charset.sgml | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)