docs: remove APISIX base instruction (#9117)

docs/en/latest/mtls.md

@@ -1,5 +1,10 @@
 ---
 title: Mutual TLS Authentication
+keywords:
+  - Apache APISIX
+  - Mutual TLS
+  - mTLS
+description: This document describes how you can secure communication to and within APISIX with mTLS.
 ---
 
 <!--
@@ -68,7 +73,7 @@ curl --cacert /data/certs/mtls_ca.crt --key /data/certs/mtls_client.key --cert /
 
 ### How to configure
 
-You need to build [APISIX-Base](./FAQ.md#how-do-i-build-the-apisix-base-environment) and configure `etcd.tls` section if you want APISIX to work on an etcd cluster with mTLS enabled.
+You need to configure `etcd.tls` for APISIX to work on an etcd cluster with mTLS enabled as shown below:
 
 ```yaml title="conf/config.yaml"
 deployment: