typo fix in pgstat.c: "exits should be exists"

[vignesh C]

Hi,

While reviewing replication statistics I found a small typo. Attached
patch for a typo in:
src/backend/postmaster/pgstat.c
................
                /*
-                * Check if the slot exits with the given name. It is
possible that by
+                * Check if the slot exists with the given name. It is
possible that by
                 * the time this message is executed the slot is
dropped but at least
                 * this check will ensure that the given name is for a
valid slot.
                 */
................

Regards,
Vignesh

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 4c4b072068..5ba776e789 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -1504,7 +1504,7 @@ pgstat_reset_replslot_counter(const char *name)
 		ReplicationSlot *slot;
 
 		/*
-		 * Check if the slot exits with the given name. It is possible that by
+		 * Check if the slot exists with the given name. It is possible that by
 		 * the time this message is executed the slot is dropped but at least
 		 * this check will ensure that the given name is for a valid slot.
 		 */