pgsql: doc: Improve description of targets for pg_stat_reset_shared()

doc: Improve description of targets for pg_stat_reset_shared()

This commit changes the documentation so as the supported targets are
documented with itemized list, making it easier to understand the view a
given target affects.

Author: Atsushi Torikoshi
Discussion: /messages/by-id/e3c25d72e81378e7b64f3c52e0306fc9@oss.nttdata.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7f6bc3b356787e5dbc0d371c9c53cb125c20cd6d

Modified Files
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doc/src/sgml/monitoring.sgml | 61 ++++++++++++++++++++++++++++++++------------
1 file changed, 45 insertions(+), 16 deletions(-)