Update postgres-changes.mdx (supabase#19368)

Fixed spelling mistake

Co-authored-by: Charis <[email protected]>

Author: CropWatchDevelopment

apps/docs/pages/guides/realtime/postgres-changes.mdx

@@ -761,7 +761,7 @@ myChannel.join()
 
 This filter uses Postgres' `<=` filter, so it works for non-numeric types. Make sure to check the expected behavior of the compared data's type.
 
-### Greater thank (gt)
+### Greater than (gt)
 
 To listen to changes when a column's value in a table is greater than a client-specified value: