configuration-file: correct the initial capitalization of certain con…

…figuration items (#19825) (#19827)

pd-configuration-file.md

@@ -491,7 +491,7 @@ Configuration items related to the [TiDB Dashboard](/dashboard/dashboard-intro.m
 
 Configuration items related to the replication mode of all Regions. See [Enable the DR Auto-Sync mode](/two-data-centers-in-one-city-deployment.md#enable-the-dr-auto-sync-mode) for details.
 
-## Controller
+## controller
 
 This section describes the configuration items that are built into PD for [Resource Control](/tidb-resource-control.md).
 

tidb-configuration-file.md

@@ -252,7 +252,7 @@ The TiDB configuration file supports more options than command-line parameters.
 > - In TiDB, the `zone` label is specially used to specify the zone where a server is located. If `zone` is set to a non-null value, the corresponding value is automatically used by features such as [`txn-score`](/system-variables.md#txn_scope) and [`Follower read`](/follower-read.md).
 > - The `group` label has a special use in TiDB Operator. For clusters deployed using [TiDB Operator](/tidb-operator-overview.md), it is **NOT** recommended that you specify the `group` label manually.
 
-## Log
+## log
 
 Configuration items related to log.
 
@@ -354,7 +354,7 @@ Configuration items related to log files.
 - Default value: `0`
 - All the log files are retained by default. If you set it to `7`, seven log files are retained at maximum.
 
-## Security
+## security
 
 Configuration items related to security.
 
@@ -445,7 +445,7 @@ Configuration items related to security.
 + Default value: ""
 + Refer to the descriptions of [`session-token-signing-cert`](#session-token-signing-cert-new-in-v640).
 
-## Performance
+## performance
 
 Configuration items related to performance.