pgsql: doc: Spell I/O consistently

doc: Spell I/O consistently

The pg_stat_io and pg_stat_copy_progress view docs spelled "I/O" as "IO"
or even "io" in some places when not referring to literal names or
string values.

Author: Dagfinn Ilmari Mannsåker
Discussion: https://postgr.es/m/87fry6lx5s.fsf@wibble.ilmari.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1f61680327c962d5bafdbf6a04ad9bb0f7232f92

Modified Files
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doc/src/sgml/monitoring.sgml | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)