Document units for max_slot_wal_keep_size

The doc blurb failed to mention units, as well as lacking the point
about changeability.

Backpatch to 13.

Reviewed-by: Kyotaro Horiguchi 
Reported by: b1000101@pm.me
Discussion: https://postgr.es/m/163760291192.26193.10801700492025355788@wrigleys.postgresql.org

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index b5d06b49e29b0a5ef165e4c3026b44809c5ed6ab..c4290b7c821f6eaa2c4cb24661290a541521f5ad 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4171,6 +4171,9 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
         to continue replication due to removal of required WAL files. You
         can see the WAL availability of replication slots
         in pg_replication_slots.
+        If this value is specified without units, it is taken as megabytes.
+        This parameter can only be set in the postgresql.conf
+        file or on the server command line.