comment fix

Author: link2xt

src/sql/migrations.rs

@@ -1140,7 +1140,7 @@ CREATE INDEX msgs_status_updates_index2 ON msgs_status_updates (uid);
 
     inc_and_check(&mut migration_version, 128)?;
     if dbversion < migration_version {
-        // Add the timestamp of addition and removal.
+        // Add the timestamps of addition and removal.
         //
         // If `add_timestamp >= remove_timestamp`,
         // then the member is currently a member of the chat.