Thread: pgsql: aio: Add README.md explaining higher level design

aio: Add README.md explaining higher level design

Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/uvrtrknj4kdytuboidbhwclo4gxhswwcpgadptsjvjqcluzmah%40brqs62irg4dt
Discussion: https://postgr.es/m/20210223100344.llw5an2aklengrmn@alap3.anarazel.de
Discussion: https://postgr.es/m/stj36ea6yyhoxtqkhpieia2z4krnam7qyetc57rfezgk4zgapf@gcnactj4z56m

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/fdd146a8ef2bc0c24e8d27e3773feeb8ef0a9c25

Modified Files
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src/backend/storage/aio/README.md | 424 ++++++++++++++++++++++++++++++++++++++
src/backend/storage/aio/aio.c     |   2 +
2 files changed, 426 insertions(+)