pgsql: doc: Remove incorrect note about wal_status in pg_replication_sl

doc: Remove incorrect note about wal_status in pg_replication_slots.

The documentation previously stated that the wal_status column is NULL
if restart_lsn is NULL in the pg_replication_slots view. This is incorrect,
and wal_status can be "lost" even when restart_lsn is NULL.

This commit removes the incorrect description.

Back-patched to all supported versions.

Author: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Reviewed-by: Nisha Moond <nisha(dot)moond412(at)gmail(dot)com>
Discussion: https://postgr.es/m/c9d23cdc-b5dd-455a-8ee9-f1f24d701d89@oss.nttdata.com
Backpatch-through: 13

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/170673a22f28bd6a1d3fa56e23cd74dcbcb60c17

Modified Files
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doc/src/sgml/system-views.sgml | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)