Update the release-8.4 directory

markdown-pages/en/tidb/release-8.4/releases/release-8.4.0.md

@@ -362,7 +362,7 @@ Starting from v8.4.0, the following contents are removed from the `TiDB-communit
 + TiDB <!--tw@Oreoxmt: 11 notes-->
 
     - Optimize the efficiency of constructing BatchCop tasks when scanning a large amount of data [#55915](https://github.com/pingcap/tidb/issues/55915) [#55413](https://github.com/pingcap/tidb/issues/55413) @[wshwsh12](https://github.com/wshwsh12) **tw@caiqian** <!--1902-->
-    - Optimize MEMDB implementation to reduce write latency in transactions and TiDB CPU usage [#55287](https://github.com/pingcap/tidb/issues/55287) @[you06](https://github.com/you06) **tw@hfxsd** <!--1892-->
+    - Optimize the transaction's buffer to reduce write latency in transactions and TiDB CPU usage [#55287](https://github.com/pingcap/tidb/issues/55287) @[you06](https://github.com/you06) **tw@hfxsd** <!--1892-->
     - Optimize the execution performance of DML statements when the system variable `tidb_dml_type` is set to `"bulk"` [#50215](https://github.com/pingcap/tidb/issues/50215) @[ekexium](https://github.com/ekexium) **tw@qiancai** <!--1860-->
     - Support using [Optimizer Fix Control 47400](/optimizer-fix-controls.md#47400-new-in-v840) to control whether the optimizer limits the minimum value estimated for `estRows` to `1`, which is consistent with databases such as Oracle and DB2 [#47400](https://github.com/pingcap/tidb/issues/47400) @[terry1purcell](https://github.com/terry1purcell) **tw@Oreoxmt** <!--1929-->
     - Add write control to the [`mysql.tidb_runaway_queries`](/mysql-schema/mysql-schema.md#system-tables-related-to-runaway-queries) log table to reduce overhead caused by a large number of concurrent writes [#54434](https://github.com/pingcap/tidb/issues/54434) @[HuSharp](https://github.com/HuSharp) <!--1908--> **tw@lilin90**