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 661bba994177e19c1b69bec79996e96a666e65f1..b2018d9763a9740aec156316cc17c2fc30b16035 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3988,6 +3988,9 @@ 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.