doc: in contrib-spi, mention and link to the meaning of SPI
Also remove outdated comment about SPI subtransactions.
Reported-by: gregory(at)arenius(dot)com
Discussion: https://postgr.es/m/151726276676.1240.10501743959198501067@wrigleys.postgresql.org
Backpatch-through: 9.3
Branch
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REL9_4_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/27a5eaa71b72866be0a63b4e68868bc87bbee5a5
Modified Files
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doc/src/sgml/contrib-spi.sgml | 4 +++-
doc/src/sgml/spi.sgml | 3 +--
2 files changed, 4 insertions(+), 3 deletions(-)