Fix comment grammar in slotfuncs.c

Author: Bharath Rupireddy
Discussion: https://postgr.es/m/CALj2ACUkrNR2xTak+QaqxoTjPKGn8zXWripv7SR27t+Q5qF1Wg@mail.gmail.com

Author: michaelpq

src/backend/replication/slotfuncs.c

@@ -414,7 +414,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 
 			XLByteToSeg(slot_contents.data.restart_lsn, targetSeg, wal_segment_size);
 
-			/* determine how many segments slots can be kept by slots */
+			/* determine how many segments can be kept by slots */
 			slotKeepSegs = XLogMBVarToSegs(max_slot_wal_keep_size_mb, wal_segment_size);
 			/* ditto for wal_keep_size */
 			keepSegs = XLogMBVarToSegs(wal_keep_size_mb, wal_segment_size);