docs(persistent_session): Apply suggestions from code review

Co-authored-by: JianBo He <heeejianbo@163.com>

apps/emqx/i18n/emqx_schema_i18n.conf

@@ -592,7 +592,7 @@ emqx_schema {
   persistent_session_builtin_session_table {
     desc {
          en: "Performance tuning options for built-in session table."
-         zh: "对内置的会话表进行调整。"
+         zh: "优化内置会话表的配置。"
     }
     label: {
          en: "Persistent session"
@@ -603,7 +603,7 @@ emqx_schema {
   persistent_session_builtin_sess_msg_table {
     desc {
          en: "Performance tuning options for built-in session messages table."
-         zh: "对内置的会话信息表进行调整。"
+         zh: "优化内置的会话消息表的配置。"
     }
     label: {
          en: "Persistent session messages"